How do I stop being such a hermit?

I was a very social person in high school and constantly hung out with people and was friends with everyone. It was after my first serious boyfriend that that all changed. It was a messy breakup and most of my friends ended up following him instead of me (since we had the same friend group)..I went on to meet someone else who cheated on me. I, then, became even more of a recluse. I am with the love of my life now and we are engaged, but I still can't bring myself to want to go out and meet people. I'm in need of real friends and I can't always rely on my fiance to be there for me when I'm lonely. He has a life. and he has his own friends. Why can't I just get out there and learn to have a little fun?