I can't get over someone and it's my fault

I think I need to get this off my chest, and any input is appreciated.Every time he messages me, my heart starts racing and I think maybe he still likes me.We were best friends, let's call him Daniel. He meant so much to me at one point, and I did to him as well.I never fall for 1) Straight dudes, 2) Guys already dating. He was someone who said he was straight, then confessed he had feelings for me. He flirted with me, until he admitted he was dating someone else. Then said he no longer had feelings for me, but that was after I started falling for him.The thing is, I'm not desperate for love, I don't think. I have opportunities to date other people, but all the dates I go on I can't connect with them. Not on the level I had with this person.Anyways, I saw him yesterday, after a while. I thought I was over it, that it was fine. But I'm in a funk now and mourning the loss of a relationship that was so meaningful. I think I need to cut him out of my life, tell him to not text me anymore.It's my fault I can't get over him, it's been nearly four months. I wish we could be friends again, but I don't think we can be. I wish we could be friends again, so badly, but seeing him just gives me pain at this point.