Should I forgive him?

I have been friends on and off for someone for 2 years. During the begining of our friendship, after being friends for some time we started dating and sleeping together. We broke up because we had to move apart and he started dating someone else almost immediately, which obviously hurt me very much. When we moved to the same town again he continued to date this girl for a few months before breaking up with her and slowly brining our friendship back together. We ended up dating again and sleeping together, but broke up again after being apart for some time. When I returned from being away we spent some time together but I knew something was wrong. Turns out he still "held a candle" for this other girl and after he revealed this to me we ended up not speaking for a long time. Now we are trying to make this work again, but just as friends. He has apologized a million times and admits he made a mistake in choosing the other girl. Is it worth it? He says he no longer has feelings for this girl, but they are still friends. What should I do?