Oh, honey...of course you're angry. Just because you are R doesn't mean you don't FEEL!
Your DDay is really recent. Non-sexual encounter or not, it is still a betrayal!
This A is NOT your fault, and you ARE good enough for him. He is the one that should be thanking his lucky stars that you are willing to work on this...and that can change at any given time. Is he showing remorse? Is he helping you get through this or does he just want it to "go away," or rugsweep?
Please don't allow this to just go away. I did that, and it happened again. That seems to be a common theme with rugsweeping...it happens again because it isn't dealt with. You don't have to do anything now, but know that just because you are working it out doesn't mean that you do all the work. HE needs to do the heavy lifting.
You have a 2-week-old baby. Take care of you and your precious baby right now. Enjoy this time with him, because it goes SO FAST! You can think about your M and make decisions later. In the meantime, make sure your WH actions show you he is fighting for you!!!!! You ARE worth it!