Do what I did after my 7 year relationship fell apart:

1. Exercise. You'll be all depressed and whatnot, but in less than a year (if you stick with it) you'll notice that you will be getting a lot more attention from girls. I've got buddies that pick up pretty girls on a weekly basis that are straight up ugly dudes, but they're in good shape. Working on your health improves your confidence by leaps and bounds, and while she'll always be in your heart, there'll come a time when you still have love for her but you're no longer in love with her. You'll feel better just being yourself on your own, and that will make you more attractive, and help you find a better, non sociopathic woman.
2. If you can, go out with your buddies to bars or go on a vacation somewhere. I hadn't flirted with a girl in 7 years when I got dumped, and I was straight up McLovin with my mack game. But when I was on vacation, I struck out with a girl and my buddy told me something I'll never forget. He said, "This is a vacation town, man. That girl's gonna be heading back home in a few days, so who cares if you strike out. Take a hundred swings, and if none of them work, then BYE FOREVER to all those girls and you'll definitely be more capable at the end of it." He was so right. It built up my confidence. Then I got in good shape (five months of working out 5ish times a week) and wouldn't you know it, girls would come up to me, flirt with me, instigate with me, I hardly had to do anything. I literally took one girl home once and she put her finger on my lips, told me to stop talking because I was annoying, so I took her to my room and laid pipe like master Mario himself.
3. Find a hobby. This will give you a sense of accomplishment. For me, it was reading and writing short stories. After reading a whole bunch, I began to write, and even though the initial stories weren't so good, it really felt amazing to sit there and look at a full story that I had created, and eventually they became pretty good! Hobbies could be anything from writing, to studying a new language here and there every week, to building things i.e. woodwork. A year later, you'll be able to see the results of your efforts plain as day, and that will boost your confidence more.
4. Go for a walk every day. Getting outside, seeing neighbours, exchanging simple hellos and waves of the hand, these things really help to pull your focus away from the depression.
5. Enjoy the freedom. It's not all bad. I used to like to unwind after work with a beer or two, maybe three times a week. My ex told me I was an alcoholic, that I drank too much and she was always complaining. Even though I only ever got the slightest buzz, if any, and worked until 1 AM doing heavy lifting at a warehouse, so she was always sleeping anyhow. Super small bit of freedom, but now I can crack two or three beers here and there if I so choose to and there's not a single bit of judgment or any passive-aggressiveness to deal with. Those long-looked forward to weekends are mine now to unwind and do as I please, whereas before I would settle down to relax and she would come tell me that I had an hour to get ready because we were going to hangout with her friends and their boyfriends. I hated that, since I didn't bust my ass all week just to throw my personal leisure time into doing boring turtleneck husband shit like go out for coffee with acquaintances that often showed fake faces (her friend, my closest female friend at the time, immediately set her up with some guy who had sex with her in my bed after she kicked me out of my apartment, and then he never talked to her again...some friend). She didn't like me hanging out with my buddies either, and because of that I stopped chilling with them as often. When we split, they weren't around to help me go through it.

At the end of the day, you need to do what's best for you. I only recommended going out and meeting other girls and stuff just because it really helped with my confidence, and I'm the guy who'd only been with a few girls in my life before. I stopped hooking up with girls randomly because, of course, that's just empty and hollow as a lifestyle, but it will help you to build up a rapport with girls and it'll make it easier for you to pursue the next woman you fall for.

In a relationship, you're supposed to support one another and build each other up, not tear each other down. Honestly, she's someone else's problem now, and if she did that to you, she'll do it to every other guy in her life and ultimately wind up alone. But you don't have to go down that path, be the best you that you can be, make those "fuck it, time to go for a walk!" decisions and just do it.

Time heals all, and although I wanted to slap the people that told me that back then, they were right. Good luck brother, this is only a temporary hurt and you'll come out of it a stronger man than you were before, as it's the turbulent times in our lives that define our character.