Depressed as lover cheated

I am a 29 year old male and was in a relationship with an 18 year old male.Its ended after a few months and we chose to stay friends.However, he could'nt accept me as a friend and often acted like we were still in a relationship and kept asking for one in return which I refused.I too loved him but would not express it to him.We would talk till the wee hours, meet up over weekends on his insistenc, have sex etc. this went on for a year and 4 months. The begigning of this month he was due to go to another state for further studies which really upset me coz I still loved him and i finally told him exactly how I felt about him even though we were not in a relationship.While in this I found out that after we split he got into a physical relationship with another guy and was in it for over 6 months. Although he says he was cajoled into it,i believe that he is responsible for his actions. he also claims that he was depressed about the break up hence fell for it.Right now i feel cheated as while he was with the other guy he still told me he loved me and was still having sex with me still meeting me and still told me that I am the only one. Now that I found out he says he is sorry and that he made a mistake and wants to start over and wants everything to be normal. I cannot act and treat him normally as be betrayed my trust. I know he loves me but if he did it once there is no guarantee he wont do it again. (he has had alot of flings before he met me which he discussed and I accepted.He wants a relationship and after this I dont feel like even commiting as I am scared now. I am so confused and clueless how to take this forward that I feel like I am going insane. Also as a result of this my job, social life , everything has been topsy turvy.I just feel so used and stupid and cheated and foolish for not seeing signs of this all through earlier My blindly trusted him and he used that to his advanage. I would appreciate if you could help me move forward in some direction.

I understand that you are depressed. He will probably not change. Either accept him the way he is or end your sex relation and try to find a partner whom you can trust. Be sure to use condoms if you have sex with a promiscuous partner.

You need people whom you can trust. Look for people who share your values.