This feeling only got worse when she sent me tons of snapchats of her and her new boyfriend a week after we had ended things.
This isn't a nice person.
I blocked her...
Good for you; smart move.
.... When I got home I had messages from a friend showing me that my Ex was now in a relationship with this boy.
If anyone else tries this with you, tell them you don't want to hear it and then either disengage from the conversation or change the subject. That was really uncalled for behavior by your pal.
.... Truth be told though, it absolutely wrecked me seeing that. I don't know what it is, but it's just brought back all of the feelings for her that I tried to move past.
That's why you don't want or need to be reminded.
All I want to do is go and try and say something to her to convince her that I'm the person she should be with, that I'm not gonna be happy without her.
I'm not going to do any of that ultimately, because I know that it won't work. What I need help with is moving past this. I realise that she didn't treat me right at all, but I keep thinking back to all the good times we had together and ignore the bad. I also realise that these things take time, but this is causing me so much emotional distress.
I've said this on a few topics lately, but it bears repeating.
Nostalgia and familiarity are powerful drugs.
Making new friends and getting into new relationships is hard work, and we, as a species, are pretty much conditioned against hard work. That's not a moral failing; it's more that getting the most benefit from the least amount of effort is a good evolutionary strategy for a lot of animals.
Nostalgia and familiarity both feed right into that, because neither of them have to get over the "getting to know you" hump that new things and people have to. Novelty is nice, too, and we also, as a species, like new things. But nostalgia in particular is a kind of cheap thrill (have you ever stopped to consider how many reboots there are these days? That comes from unambitious money people at publishing houses and film studios, but also from the fact that nostalgia sells).
Anyway, the point I am making is that there is a powerful pull back to what once was. But you're also, like Found Soul said, only thinking about what was positive about those times. There were plenty of negatives, too. Don't dismiss them.
And like I wrote earlier, she is entitled to her new relationship, but if she has any sensitivity at all, she would be a bit more selective about who she tells about her new boyfriend. Shoving it in your face like that was the antithesis of kindness.
And finally, be good to yourself! It's only been a month. The end of a relationship is like any kind of loss. You mourn. So do a little mourning. Give yourself some time to catch your breath. And if another one of your buddies tries to share some story of her life with you, derail the gossip train immediately and talk about anything else. Her new life, at this point in time, is not something you are on a need to know basis for.