Hi qazi -- Actually their lives shouldn't really affect you at all. Yes, it's difficult when parents divorce, but it's really THEIR business. It shouldn't affect YOUR relationships at all. It has nothing to do with YOU at all. Nothing -- unless you LET it. And you shouldn't.
The divorce was between THEM, not you. You weren't involved in it at all, and you didn't cause it. They just could not get along. I find it strange that they're still living in the same house -- I assume it's due to financial reasons, correct? It must make it very uncomfortable for everyone.
I would suggest that you get some therapy, since your relationships SEEM to be affected by their divorce. There must be some underlying reason for this since you had a long-standing relationship before, and now they're ending badly. I think you should talk with a therapist about this and find out what's going on. Personally, I think you're angry about your parents divorce, and you aren't able to handle it well. So seeing a therapist would be best -- he/she would be able to help you cope with the situation and give you the proper tools to deal with it.
I wish you the very best. Please let us know how you do -- God bless and take care. Hugs, Lee