I think you need to spend some time on your own, building up your confidence, and being happy in your own skin, before you even contemplate being with anyone again.
Without knowing the ins and outs of your previous relationship, it sounds like he did things that were designed to make you feel insecure - having the EXW always around in the wings, for example. You reacted to that, so he gets to say you are jealous and insecure, and therefore difficult to be with. But a normal relationship wouldn't have a guy parading his ex like that (or allowing his sister to do the same). Do you see what I mean? He was setting you up to be insecure, because that's where he wanted you.
I've had a relationship like this in the past - the boyfriend playing me off against his ex(es), and me like a mug, falling for it hook, line & sinker, wanting to prove that I was more desirable. Not just trying to prove it to him, but also to his family. I remember well the arguments that were so twisted, I would never be able to win - I remember just weeping and weeping, because it seemed like utter madness - I just could not get him to see sense or my point of view.
Now, years later, I realise that it was just never going to work. We were two completely different sorts of people (me sane, him a complete emotional fuck up), and although I haven't thought of him in years, I am in no doubt that he is still a complete fuck up. Meanwhile, I am happily married with 2 wonderful DC (well, apart from the usual moans, but I have a normally wonderful man).
It could well take some time for you to find yourself. I ended up travelling round the world, several years later, before I really felt truly comfortable with myself. But you sound like a good person, who just needs time and space to get over this. If you think how long you were together, of course it is going to take time. Be kind to yourself.
Did you get anywhere with booking the Freedom course?