Cheating partner

I have a 2 year relationship with the father of my baby girl. We aren’t married. Recently a friend of his, who happens to be my colleague at work, told me he is cheating on me. I was already suspicious about this and her saying it just confirms my suspicions. I have no proof and wish to have one so he can’t deny it. Also, I feel so hurt I want him to feel bad with my withdrawal of love.

I feel powerless. I don’t know what to do. I wish to give my child the family I didn’t have, father+mom type of, but in the other hand I don’t trust my partner anymore of something I don’t even have proof of!!