Is it normal to feel this way while you're in a relationship?

I'm single but my last relationship ended because of me. I didn't do anything wrong but I was unhappy. I was unhappy because I felt like there was something better out there for me. He was a great bf, it was a fun, healthy relationship. Nothing wrong until I started feeling I don't know...bored. Not only did I want to be single but I felt like there was someone else who can offer me what I wanted. So we broke up and planned to keep in touch. So far its okay keeping in touch but I do feel like I'm going to lose my best friend. He was my best friend, he understood me, I felt like I can do and be anything around him, etc. But like I said earlier, in terms of a boyfriend and relationship I felt like there was something better for me. But now that I'm single, I have been talking to guys but I haven't felt that comfort I felt with my ex. Even when those guys have what I like, I'm still not 100 percent me. So I am torn. Do I go back with my ex because it seems like he is the right one for me considering all these guys? or do I move on and hope to find someone like him plus who has what I want? There's just so many people out there that yeah I have a chance to find someone yet there are so many people out there that what if I just never meet another one like him ever again? Right now I feel lonely, sad, depressed, and I need someone to comfort me and that's him. I plan to see him and maybe we'll see how we feel around each other. Maybe it isn't the same or maybe sparks will fly again and kinda make my decision already. So what do I do? I'm so torn about making the right decision because I don't want to hurt anyone, not me and not him.