So here's where I am today

I am really struggling with this concept... I am having a hard time making myself believe that his "charming" persona, which was what I experienced in the Honeymoon Phase, and what he acted like around everybody else (even his family), isn't actually the real him. I mean, I am the only one that he acted immature, cold, angry, manipulative, and vindictive with, so maybe there was just something wrong with me that caused him to act that way towards me.
And how can I be sure that the OW (who WAS my friend that I introduced him to) won't only experience his wonderful charming side. I mean he spent the last 4 months that he was with me, falling in love with her, and flirting with her/romancing her behind my back, having sex with her behind my back. I am terribly jealous of the fact that he is now spending all of his time with her and hasn't even thought of me the whole 2 months I have been NO CONTACT.
Why am I struggling with these thoughts every waking moment??