Can't let go of what I remember

Well I was with someone for about 13 years then about 2 years ago he passed away. Well someone that had been friends with the both of us.was really there for me during this hardtime well of course one thing led to another and we started seeing eachother. And we had been together ever since all up untill about 3 months ago. We were having to stay with some friends. Cause we were inbetween apartments when he just up and left me. Well I got really really depressed ( I should probably tell. You that there is about a 15 year age differencebetween us) and started drinki@__ng alot. Well finally I started to snapp out of it.well we started seeing eachother again. Then ai found out that he had moved in with his babymomma.I know he did this cause she is financially. Stable and has a house. See but we arw still seeing eachother every chance we get .He has told me . As soon as I get on my. Feet he will come back.I know this is a very disfunctional relationship but I am still very much attracted to him. As well my daughter that is 20 years old is very close with him as well he treats her like she was his own daughter. The thing is I think ai know what I should do but my heart just wont let me leave him.So my question is what should I do?