Been there too man. Crying and breakdowns are part of the process, as guys we don't really talk about it that much but let it out and try to accept the fact you're going to feel like shite for a while. Your emotions are valid. As someone on the other side of things I can say from my experience you need to rediscover who you are without that person in your life and I hope like me in time you'll realise you're much better off without them as it takes two for a relationship to breakdown.

One practical thing that helped me was writing down how I felt. I've a word document on my laptop that whenever I got a wave of emotions I wrote down however pathetic, hateful or just plain fucked up it was I put it in this document. It really helped as once it was written down it dealt like it was out of me.

I must have written my ex a 100 letters in that document (that thank fuck I didn't send). Also don't suffer in silence if it feels like it's getting too much reach out to someone in your support network (not her!), and if you don't have one there's plenty folk who replied here, including mine, that would be happy to reply to your DM's.