Has anyone ever dealt with this

So my best friend Ian and I have been really close for a long time obviously. I thought he wanted to be more but he wouldn't let me kiss him i thought he was just being a gentleman. He told me he liked me but then I found him in bed with my brother Mickey I don't know what to do how to handle this or how to confront him I don't want to loose our friendship but now i feel awkward that i pushed myself on him but his brother isn't bad looking either maybe he's not gay