Not knowing your S/O has hepatitis b!

So my mom just called me crying because her husband of ten years never told her that he has hepatitis b! They are in the process of divorce and it only became known because his sister told my mom under the impression he had told her years ago. She hasn't confronted him about it because nothing is finalised and she doesn't want him to take anything else away from her.

To be clear, he cheated on her and then told her that he couldn't handle her new found Godly path and that she should be on her own. I never really got along with him growing up so I'm glad she's getting out of a bad situation but she never saw it as bad until now.

Now she has to go through and get testing done but is worried she can't afford it. I told her that she needs to make him pay for it since he never told her.