Busting, I wish your Mom a full recovery. The attitude is a big deal, and it is great that she is in good spirit.
As for your H, I know how frustrating it is when you see some positive steps and then there a few steps back... The OW addiction is hard to break. Let him deal with it. It is very important to keep giving him space and not pressuring him now. I think you are right to enforce the boundary though. Take a deep breath and continue to be the wonderful you – for you.
M:50 H:52 S28 (my S from previous marriage) M:17 + 3 BD: 06/12 S: 06/12 - H works in another state