A fresh start

So my SO and I just went through a break of sorts. We've been together for almost 3 years and I love him dearly. I broke up with him because I had seen that he was talking with another girl.

We broke up for about a month and have gotten back together after a long and rough month for the both of us.

We both did some things that we regret and I know that he loves me but how/when do I start to trust him again? I don't want to seem crazy and I just want to be happy with him.