I'm sorry that it has taken me so long to respond. I hope that this note can still be a help to you.
I am sorry to hear about the problems that exist in your family. Your dad was wrong in having the affair, and many times the results from sinful decisions last for many years. The fact that he came home does not undo the emotional trauma that took place when he left, and it would have been nice if he had realized that.
At the same time, there is nothing that you can do about what happened all those years ago. It does seem that you are carrying bitterness against your dad which is going to continue to tear you apart. Hebrews 12:15 reads,
"lest any root of bitterness springing up trouble you, and thereby many be defiled."
I think that this has been going on in your life for many years, and it is affecting you. What can you do about it? Ephesians 4:31-32 states,
"Let all bitterness, and wrath, and anger, and clamour, and evil speaking, be put away from you, with all malice; And be ye kind one to another, tenderhearted, forgiving one another, even as God for Christ's sake hath forgiven you."
You need to choose to stop being angry and bitter, and start treating your dad in a loving manner, not only outwardly, but in your heart as well. Your dad did a terrible thing all those years ago, and it appears that perhaps he has not handled it the best in the years in between, but you have to decide how you are going to handle it. The Bible tells us that we can respond to others in two ways. Colossians 3:13 tells us that we should be "Forbearing one another, and forgiving one another, if any man have a quarrel against any: even as Christ forgave you, so also do ye." You have a quarrel with your dad. You have to either choose to forget about it and move on (forbear), or talk to him about it and give him forgiveness. Either way, it has got to be over. If you choose to talk to him and he won't talk about it, then you have got to choose to let it go.
You stated that what your dad did changed your relationship forever. Did he change, or did you change? Did he not want to reconcile with you, or did he attempt to reconcile with you, and you refused to allow it to happen? What did you want him to do to resolve things with you? You were only nine years old. A man that is weak enough to have an affair and move out probably doesn't know what he should do as far as dealing with his kids is concerned. He probably assumed that he had taken care of things with your mom, and that was all that he needed to do. I doubt that he felt comfortable sharing intimate details of immorality with you at your age, and he probably believed that you would just forget about it. I'm not saying that he was right in those thoughts, but it is what happened, and you can't go through the rest of your life dwelling on it.
In the same vein, why have your parents not helped you with college, or provided anything for you? Has this distance been caused by him, or by you? Does he want to help, but you won't accept it? Has he tried to do things with you, but you won't let him? Perhaps the problem lies completely with him, but since I don't know, I have to ask. If you aren't allowing him to get close, then you need to allow it. He is your dad, God gave him to you, and you ought to treat him with love and respect. Is it possible that he doesn't say "I love you" because he knows that it will fall on deaf ears? Again, I don't know the situation, but you asked for advice, and I am trying to give you some things to think about.
As far as ______ is concerned, you are completely in the wrong by sneaking around behind your parents' backs. They are still your authority, particularly if you are still living at home. As I read the Scriptures, a daughter is under the authority of her dad until he gives that authority away to her husband at the marriage ceremony. Thus, you should listen to what he says. I don't know why he says "No" to your dates with ________. Maybe he has a good reason. Apparently he wants you to spend time with _________, but only at your house. There may be two reasons for this. First, he may want to see you practice courtship rather than dating. There are many different views as to how this should be accomplished, but the bottom line is that couples are never alone with each other, and the parents are very heavily involved. Second, he knows from experience what can happen in a church setting when you are alone with someone of the opposite sex, doesn't he? He had an affair with a woman from the church. Perhaps he is trying to protect you from ruining your life like he did his. Again, he isn't keeping you from _______ - he is only keeping you and ______ from being alone. That is not necessarily a bad thing.
The fact that you have chosen to rebel against your parents and disobey them is troubling. You defend your actions by blaming them for their "lack of love", but that is no defense. I am to obey God and the authority He places over me regardless of the problems that the authority might have. Just because your parents may not be right with God doesn't meant that you can rebel against them. The fact that you are so bold in your rebellion as to say that you don't care makes me question whether you are walking with the Lord yourself. Perhaps you need to do some soul-searching, and you may need to repent yourself, both to God and your parents.
As long as we are on the subject, does ______ know that you are sneaking out in rebellion against your parents? If he does, and particularly if he is encouraging it, that presents another problem. I Corinthians 13:6 states that true love "Rejoiceth not in iniquity, but rejoiceth in the truth." If he really loves you, he won't be happy with the fact that you are sinning against your parents, and he certainly won't encourage you in your rebellion. He will want you to have an honest relationship with them. Speaking of love, do you love your dad? Again look at I Corinthians 13:5,
"Doth not behave itself unseemly, seeketh not her own, is not easily provoked."
Does that describe you? Are you behaving? No. Are you acting selfishly? Yes. Are you angry and upset with your parents? Yes. Perhaps you need to re-think some of these things. Perhaps ______ does too, for a woman who is rebellious against the authority in her parent's home will probably be rebellious against the authority in her husband's home. The problem isn't the home, the problem is the attitude of rebellion.
You are getting married soon. Assuming that nothing changes, in three months you will be in a new living arrangement with your husband, and you will not be dealing with your parents on a daily basis. Even if they were 100% in the wrong, you can handle it for three more months. However, they are not 100% in the wrong. I would advise you to be the right kind of Christian daughter for these last three months. Attempt to reconcile with your dad. Stop living in rebellion. Practice forgiveness and forbearance. Put away bitterness. Practice Biblical love. Stay away from situations which might lead you into sin. Remember, the decisions you make in the next three months will impact your marriage and the remainder of your life. They will influence your children, for the law of sowing and reaping is still in the Bible. They obviously will influence your relationship with the Lord. Make the right choice.
You mention being raised in a Baptist home and going to a Christian college. I am making the assumption that you have received Christ as your Savior at some point. Of course, if you haven't, that needs to be your first choice. Being a Baptist doesn't make you a child of God. If you are unsure of this, please write me back so that I can help you.
This letter has probably come across harsh, but since I don't know all the facts, I have to try to cover all the bases. Please give it some consideration, and may the Lord bless you as you follow Him.