<human>: Summarize the given text in a few sentences.

We dated for 2 years and got engaged a few months ago. We fell for each other fast (or so I thought). At the beginning of our relationship his ex emailed me (she found me on facebook) and told me that he was a cheating asshole and was trying to get back with her- that they even had sex when I was out of town. My bf denied everything and, although apprehensive, I believed him. 

Months later, he had to go out of the country for a semester. We talked as much as possible, web chat, emails, etc. I found pics of him on facebook, with another girl. He said they were just acquaintances. I never completely believed him but, tried to ignore my gut feeling because I loved him.
When he got back we had a huge fight. I found that he had told me several lies about himself and his family. He begged, pleaded and apologized, and promised to be honest with me. I decided not to break things off. However, I also suspected him of cheating on me, which he still denied, and I never had any substantial proof. About a year later he proposed. Something didn't feel quite right, however. I still didn't trust him and tried to contact the girl I believed he had cheated on me with. We talked for about 30 minutes and I found out that he not only had sex with her, but carried on a relationship with her for 4 months. I broke off the engagement. He admitted to having sex with her, but nothing more.

Whenever we were together, it was wonderful. We had passion, love, supported each other, laughed with each other, and had the same religious and political beliefs. It's been about a month since I broke things off and he desperately wants to try to work things out. I love him but the trust isn't there. He says he will do anything to earn back my trust. Should I forgive and try to work things out with him or carry on without him?
<bot>: Bf of 2 years was a compulsive liar and cheated on me. Desperately wants me back but not sure if I should give him another chance.