His response to you asking him about what you have uncovered seems typical of an addict. His response sounds to me like he wanted sympathy for his internal issues that he says made him act as he has...
Having a young child with a man who may or may not be engaging in extra marital sexual behaviors is alarming for many reasons not the least of which is because of disease concerns etc...
I would be thinking about yourself and what you can do to keep you and your child safe... Maybe while your husband is figuring himself out, he needs to be elsewhere?