I was with a girl for over 3 years. Supported her through having a brain tumor and 2 brains surgeries, and helped her out in so many other ways. Her family isn't very well off, I did literally everything I could for her and she ended up cheating on me with one of our mutual friends who is dead to me now.
After the breakup I shut her out of my life completely for a few months, then that summer ended up "seeing" her again a few times, against my better judgment. I was really lonely and had a lot of feelings for her, and it's so easy to get back into it with a person who you've been through so much with.
We still talk, I never contact her though. She has a boyfriend, yet sends me random texts saying we're soulmates and all this shit.
My advice to anyone going through similar breakups/problems/depression:
1.) Try and go on dates with other people-lets you see that there ARE other people in the world, other people who won't put you through shit.
2.)Stay busy, go skating with your friends, go to shows, movies, whatever-just don't stay in your room all day alone with your sad thoughts of regret.
3.)Let them contact you. If they don't contact you, then it's for the best. You'll see they didn't care about you. And If you contact them they' won't appreciate it anyway. Lots of girls are seriously so regular in that manner. They basically want a guy that acts like hes too cool and doesn't have time for them. Thats why you should never become whipped as the girls in the stories have said they wanted-as soon as you change for the girl, she'll lose interest and find someone else, someone way shittier usually.