How do you go back to being alone?

So I just recently went through a breakup where it lasted for 2 years and was my first serious relationship. Previously I had a hard time opening up to people and be vulnerable as I don't like being dependent on other people. We were very happy and we love each other so much, but he has a lot of issues as he is suffering from bipolar disorder, depression, and a compulsive liar. It created a lot of problems in our relationship as we kept hurting each other unintentionally. It made me think that we weren't right for each other because we have tried so hard but came out with nothing, So I ended it because I don't see our path getting any better and it was the hardest decision I've ever made because I still love him very much and I know that decision hurt him a lot. He hates me now, he thinks I gave up on us and broke his heart, which is true. So it is very hard for me right now, because I'm still very much dependent on him, I really need him but he shut me out. Something I very much understand because I'm the source of his pain and he needs to get away from me. But I just miss him so much and I just wish I could still talk to him. Now I don't know how to be back of being alone as I was so used to having him and sharing everything with him. I honestly don't know what to expect by joining this community, I just hope, somehow, miraculously, it can help take away some of my pain and help me move on.