I have been dating a man for 7 years and it is at the end he is very obsesive what do I do?help............?

I have been in a relationship for 7 years.It was all great up until the last three years of it.We moved in together and that is when it all changed he started to drink.He started to gamble all night long and not come home until about 5-530 am not knowing where he had been all night!Bc he would go there right after work and not call me and just say he never got paid for that week.So this went on for weeks which turned into months.Finally I said enough is enough.Well after realizing he had a problem(gambling) we lost our apartment(evicted).Yes I was working but not making enough to pay for all the bills.So I am living at home now and have been for the last two years.He lost his job has no car and basically stays with friends.But he will show up over here when it has been a week or longer.But back in April 29th he stayed gone for 12 days no call or nothing not knowing where he wa at was very worried.He finally had called me on may 10th .We broke up on the phone b/c I could not take it anymore.Alos his friend that we had lived with for awhile told me they had a relationship with HIM.........NOW he is suppose to be straight so I thought.So here I am at my friends house and he is telling me all this stuff about my boyfriend.He has had a boyfriend and a girlfriend the whole 7 years we have been together.I HAD NO EARTHLY IDEA.........So when he had called me on may 10the I never said anything abot me knowing all that info about him.Bc he will just deny it....We are still broken up but we have been talking and he wants me back but me knowing all that it is not the same now.I need to know from all of you readers out there should I tell him or what?Bc he thinks that I am onl breaking up with him bc of the twelve days he was gone.I did make a promise to our friend about not saying anything to him about what he told me about my boyfriend.PLEASE HELP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!