I'm a 38 year old female in a relationship with a 39 year old male of 1 year and desperately need advice 
We met a year ago on P.O.F and everything was going great until I found something that broke my heart. I found he had cheated with another woman at the start of our relationship, was messaging her and others up to the end of last year and he then admitted to having strong feelings for a 'friend' for the majority of our relationship. He has a 6 year old daughter with brain damage that I've bonded with and love very much. I've no children of my own and he has just stated that he will not have any due to the possibility of a second child with the same condition.
I'm devastated and feel as if everything I thought I had, or could have had is gone. And feel as if it's too late for me. Do I stay and try and rebuild or do I go and try and rebuild my broken life and heart.
Any help appreciated!