Stuck in the Middle

I went out with my boyfriend for 1 year and 2 months. We loved each other very much, but the more he hung out with his single friends, the more he missed it. One day he started talking about not knowing what he wanted, so i made him choose between me or being single. He chose me. I knew he still wasn't completely sure of his answer, and i didn't want to take the risk of having him leave me later in the relationship. So i told him to really think about it and let me know what he really wanted. Like i thought, he chose to be single. A day after we broke up, he started talking to his ex-girlfriend again (I had made him stop talking to her about 2 months into our relationship for personal reasons). Then, 2 days after we broke up, i found out that he hung out with his ex and they kissed. I thought he was moving on for sure. At the same time, i was talking to a friend that i had known for about 5-6 months. He was a really good friend, always gave me the best advice, and helped me through my break up... i guess you could say he was my best friend. Since i thought my ex-boyfriend was moving on, i decided i should try and do the same. I hung out with my best friend one day.. and we ended up sharing a kiss. I told him i was catching feelings for him, and he told me he was too. A few days later of hanging out and talking my ex-boyfriend calls me.. he starts telling me how much he wants to be with me and how much he regrets breaking up with me. He told me that i was the one, that he now knew what he wanted and it was to be with me. I am super confused right now! I don't know what to do because i fell for my best friend.. I'm caught in the middle. I would love to be with my ex-boyfriend again, because he meant so much to me. We shared many things together. We had a bond like no other, and it would be hard to just let that go. On the other hand, however, my best friend is such an amazing guy.. I trust him with everything, and i would hate myself for leading him on and then just telling him I'm getting back with my ex. Especially because that might not be what's best. I honestly don't know what i want right now, I'm really confused. If i end up choosing to get back with my ex, it might ruin the friendship i have with my best friend. But if i choose my best friend, i would have to let go of everything i had with my ex, and I'm not sure i want to do that.. its been so much. Help! I don't know what to do! :(