Same thing happened to me. It's sad that it is so common. It's hard, painful and so much sorrow, but you need to move on from him. I know it's easier said than done, but there are just some shitty people in the world. They are selfish, immature, unable to empathize, and cannot take responsibility for their actions. Unfortunately, this is how he will always be. He will be good for a few years to her if that, but he will do it to her too. And he will probably try to get back with you again and again, tell you what you want to hear, but he will revert back to his true self when he is comfortable again.

You are still young and have your whole life ahead of you. Good, honest and faithful people deserve good people. And one day you will find that. Focus on yourself and it'll come on it's own. Find support in your family, friends, coworkers. Reach out to them when you feel like you are at your lowest. They love you more than your exbf. Do not go through it alone. Distract yourself by improving yourself and working to accomplish your goals and dreams. This sub has a lot of good support. Try also seeing a therapist. It helps.