Someone else I'm sure will have a better answer then me but here's my take on it. I know almost exactly how you feel, been there not to long ago. You need to focus on yourself and get yourself to the point where you know that you will be fine no matter what happens with you and your husband. If you can truly feel this you'll be fine.
I still struggle a little sometimes with the snooping but I just have to remind myself that the only thing that this will accomplish is hurting me. Therefore there's no point. I'm at the point right now where I can honestly say I know I'll be ok with whatever happens to our M. This has dramatically improved my PMA which can do nothing but good things even if it's just for me.