Jenna - take if from another who is living this too. The road back for your spouse will not be a smooth upward progression to a new relationship. It will be a series of ups and downs but overall you hope it will get better.

He is showing signs of getting it together, although be careful its not just an immature kid getting off on the high of the emotion.

If you love him and your M, and you know your boundaries, and he is doing the work to rebuild himself and the M then maybe its worth letting this playout.

I understand your thought process about how you deserve better. I wrestle with this too. You do deserve better, but maybe that "better" is with a H who has grown. Maybe give this a chance?