How to overcome extreme jealousy of my ex and the girl he fell in love with?

My question is actually not about this guy but about your other exes who all came back. It is rather unusual for exes to do this unless they are emotionally unavailable (and then they end things but eventually want to keep the door open and come and go, or realize after you’re gone that they want you only now that they can’t have you and you’re no longer available to them, etc). For it to be a pattern that they all come back suggests you are choosing men who aren’t ready or emotionally available to be fully committed to you. I think this even more from your comment that this guy who did not end up being great to you was the best boyfriend you’ve ever had. That says nothing about your value at all, but it does suggest there may be a problem with how you’re choosing your partners. When there is a pattern to the type of people you date, it is often a mirror you can learn a lot about yourself from.

My inclination is to say that if this guy fits into a pattern of similar bad dating experiences, then his flip is far more likely to be a result of his own issues than anything you did or even of him never caring about you at all. It isn’t that black and white, and telling yourself you must be an unloveable piece of trash for him to make the choices he did is neither helpful nor true.

I’m sorry you’re in so much pain, but neither trying to figure him out nor beating yourself into a pulp will help you here. He’s fickle and a bad communicator (this is clear if he was having doubts prior to reconnecting with this woman and still blindsided you totally). You need to focus on yourself and rebuild your self-esteem. You invested so much in someone you only dated for a few months that you don’t know how you’ll survive because you lost who you are. That’s not a healthy way to be, don’t abandon yourself. You’re worth more than that, but you’re also the only person who defines your value so be kind to yourself.

Your last paragraph was a little dramatic, so it might help to put things into perspective. This guy wasn’t genuine with his emotions (nor his actions, I assume) and he’s moved on to the next one. Who knows how long he will be with her — it doesn’t matter. He’s given you the gift of showing you who he is by his actions.

To be fair, we honestly don’t know (and it’s highly improbable) that he’s “in love” with this new girl. Infatuated, definitely!

The best way for you to move on and “live through” this is give yourself a small window of time to be sad, angry, watch a bunch of man-hating movies, then pick yourself up and focus on doing things that make you happy. It helps to get outside your own head as well, so things like volunteering or spending time with your friends and family help. If you don’t feel you have a strong support system, maybe find a counselor to talk to for a while, to help you work things out.

You won’t always feel like this. It’ll get easier, just like everything gets easier. I don’t mean to sound overly cynical or discouraging, but you’ll probably experience worse heartbreak than this in your life, so take stock of your blessings now.