I see this thread was started around a month ago so is the OP still around to talk about it further?
What makes you think you overreacted?
I know of a child in a similar situation (social services monitored). I won't hijack the thread with another story but just to say I understand something of what you're going through. I have a feeling that the child I know may one day vote with their feet - as you have done. I also know that the child loves the parent wholeheartedly and feels the parent to be fun to be with, neglectful behaviour aside. Does your dad have any redeeming qualities that you feel may draw you back? If not, what do you think it is that makes you want to give things another chance?
I am sorry he couldn't accept you being bi or gay. It must have been difficult to come out to him if he was so bad to you. Have you talked about it with your mum as you appear to be okay with her?
Can I ask how you know about his cardiac enzymes and heart attack? Does this make a difference to how you feel about him?
From what you say your mother knows how he was with you. I'm interested in understanding why she feels you should talk to him? I also note your dad appears to have a good relationship with your brother. Does your dad get on with any of the other relatives and could they, maybe, help with mediation if you do decide to talk to him again? Mediation is a powerful tool in relationship healing/building if used properly.
I don't even know what I'm supposed to consider in this situation. how do i even start to think about this?
I would start with talking this over with someone in confidence such as a counsellor or even your local vicar (or whoever your local church person is). You don't need to be religious to approach one or you could try a mental health charity and I'm sorry but I wouldn't know who they are in your country.
Whatever you decide take your time. When someone hurts you the emotional wounds go deep and last long. It wasn't your fault but you need to heal from that first. This may be a contrary thought but I do believe in talking things over as part of the healing process - once you've dealt with your own feelings.
I hope that helps a little.