Wouldn't this be a lot easier if we had that crystal ball telling us how everything would play out?
I'd sit back and just watch H for a while. And cut off all the flirting with OM. (flirting with men has never been my thing anyway)
These flirty relationships only cloud your judgement of H's progress, if there is any, and are likely to develop into EA/PA that will eventually crash and burn just like H's A did.
I didn't say this would be easy, and you will go into a mini withdrawal when you do this. The longer you carry on a flirty relationship (or EA/PA) with OM, the worse the withdrawal/grieving will be. Again, look at H. Do you want to be broken like that? I wouldn't.
Time is on your side here TG. You've come so far and worked so hard on yourself to get to where you are, and like Tori pointed out, this may be your big chance to renew your M with H. It will still take plenty of time though... H has a long way to go.
I might swing a 2x4 or two, but I certainly don't want you to feel bad about anything you've done. You've been spectacular through all this, and are only human. Bust On!
M: A really long time. Crisis: 5 years. She's still worth it.
Life is never made unbearable by circumstances, but only by lack of meaning and purpose. -Viktor Frankl