Sorry, but I think you're focus on her is letting your husband off the hook. You're trying to pin it on her, pretend everything would be rosy if only she had never entered his life.
That's bollocks.
The fact is that your husband is the instigator here, and yes that really really fucking hurts. It hurts that he's hiding his interest, it hurts that he may have done this before, it FUCKING HURTS. But it is your husband who is hurting you, not her. NOT her.
You've said yourself that you "don't think she is interested in him... unfortunately I think he is interested in her!" That is what you are dealing with, not an OW - she is in no way an OW!!
"I do think she's enjoying the attention, even if she's not interested enough to do anything about it. So no angel!" Oh FFS, you're trying to shift the blame off of him again!
This is all his fault. His, and his alone.
"He's now blaming all this on my jealousy and how he thinks I'd react if he hadn't done those things"
I don't know if you are a jealous person, I have no way of knowing. You might be. Or he might be trying to gaslight you to wriggle off the hook. Either way, you are unhappy and I don't think you are going to become happy in this marriage any time soon. You're either married to a man hoping to cheat on you, married to a man who behaves in a way that sparks jealousy, or a jealous person who will always be suspicious of your partner. Whichever it may be (or something else) - your marriage is dead in the water. Sorry, but it is.
For your own sanity, step away from this woman's social media. She is not the problem, he is. Your focus on her serves no purpose but to shift blame from his shoulders, where it rightly belongs.