You've been so strong, Nikki -- don't stray from this now! Yes, H is really struggling with himself right now, and all you can do is be there for him. Maybe he did come back too soon, maybe he still is involved with PW. Just continue being the new you (and you're doing a great job here!), continue showing him appreciation for both the small and big things he has done and continues to do (like opening up to you -- good job on letting him know!). Positive reinforcement is a key tool that your H needs IMO. Tell him you appreciate him for continuing to try -- and don't just tell him, show him.
Keep a PMA -- he opened up to you about this, which in my mind tells me that he is willing to show you he is vulnerable right now and is actively seeking your support. I know that he may not be making the best M saving choices right now, but remember that he doesn't have the tools that you do right now either.
Stay strong Nikki -- validate, support, appreciate. Yes, you know these tools, but remember that they are tools to use continually, and that it will take lots of time using these tools to rebuild the M. Don't fall back into the trap of old ways -- be the woman that you would like to be and that H would like to be with.
(((((Nikki))))) You can do this!!! You've done too well and worked too hard to give up right now!