You are so new to this whole thing - please give yourself a break. It's very difficult to let the feelings and the dreams and the memories of what was/could have been go. Anger and anxiety are all part of this crazy ride.
With that said, I have a few thoughts on your post.
First, we all did it in the beginning so this is not a judgment or a 2x4, but you are making excuses for your wh's behavior. His mother pushed him to it, there are lots of stresses in your lives, etc. We all have stressors in some form or another - jobs, kids, homes, bills, family, etc. You lived with the exact same issues, but you didn't choose to cheat. He chose that path; nothing forced him into it. For whatever reasons and whatever problems he felt he needed to escape, he decided that, of all the possible solutions he could have explored, having sex with someone else was the best. Even if R is ever on the table, you - yourself - have to get to a place where you acknowledge that this was his choice and that something inside of him made him lean toward that horrible choice. If you don't acknowledge it and he doesn't acknowledge it, any attempt at R will be nothing but one giant rug sweep and you will be afraid for the rest of your life when he hits another rough patch (and he will) and you will wonder whether another A is coming.
Second, you cannot fix him and you cannot control whether he goes back to the AP. Nothing you do - and I mean nothing - will have any bearing on that. Remember that the A was not about you or anything you've done. It's all about him. You can't nice him back in. You can't reason with him. You can't say that one magical thing that will make him sit up and say, "aha! She's right!" This is why NC is the best thing for you. He doesn't matter right now - NC is for you and your emotional health. Again, even if R is ever a viable option, NC will make you stronger and put you in a position where you can evaluate whether trying to save the marriage is the best thing for you. It will help you break any tendencies toward co-dependence and allow you to make decisions all on your own and in your own best interests.
Lastly, staying busy is a great idea, as well as reading/posting on SI, exercising, going to IC, and being with your friends and family. At the same time, sometimes you just have to lean into the pain and acknowledge it. There is no amount of running or painting or cooking or anything that will just make this all go away in one instance. It takes time and I know that is a filthy word for someone in your state, but that's what it takes. Time and the desire to climb out of this hole, whether he's next to you or not.
You will be ok. Keep focusing on yourself and taking those tiny steps toward your healing - one day at a time.