If there is another woman, you can't do anything but DB. I say don't worry about it (knowing that is impossible) but you can't do much about it except reinvent yourself and make yourself happy.
As far as child support...hmmmmm. What are the laws in your state? I would look them up online, then write a letter to him so you have a record for later. Ask for whatever is fair for your child according to the laws. A simple straightforward letter, not mentioning the R at all. Quote the state statute so he knows you did your homework and are serious.
You are probably going to get what you ask for, plus perhaps a panicked reaction from him about the sitch too. Stand firm if/when that happens, then you will be in control of the situation and will have some ability to make it come out as you wish it.
If I were you, I would place the emphasis on your son and yourself first, then your job, your family and finally your H. He can move up that chain if you deem him worthy sometime down the road.
