Should I forgive my X?

We've been together for 6 years, its a long distance relationship and I know I love him and want to be with him forever, but we broke up on Sep 2010 because i found out he cheated on me, we didn't talk for about 3 months until he came back asking for forgiveness, and I really want to forgive him, but I doubt that ill ever trust him again. Can I be in a relationship were I can't trust my partner?