Well, I guess you already know that contacting OW isn't a good idea. Truly, she is nothing to you and not worthy of your valuable attention - she is your H's problem. Plus, it looks like a desperate move to try and win him back - which backfired sadly.
Do recognise though, that whilst he may say all of this right now - it may not always be the case. My main worry for you is that of not following the DB rules. You've 'gone off on one' (ie FB PM) and didn't post here for advice at all - then you came back here to post when it's time to try and pick up the pieces. It's a bit frustrating.
I would suggest you have a look at the 37 rules - laminate them, read them every day in earnest and really start to 'live' the rules in your daily life and any interactions with your H. However, I don't believe the situation is hopeless. It only becomes so if and when you give up hope....and there is a rule about that too of course.
For now, regroup and leave him (and definitely her!) alone and focus on your own DBing efforts and moving forward from this episode.
I'm sorry if any of the above sounds blunt at all - I don't intend it so and only hope to help. Take care my friend xx
T 13 M 7 Me 48 H 46 SS 15 BD 7.14 PA D final 5.16 (H filed)
We receive & we lose, and must try to achieve gratitude & embrace with whole hearts whatever of life that remains after the losses - Dubus