Fancying a family friend feel so awkward

I’m not saying I’m breaking up a relationship before anyone gives me any hate so please read before the trolls kick off.
I have known this guy for yearsss now his my brothers friend how I know him his kind of part of our family ( we have different friendship groups ) there’s always been a little thing between us but never anything further has happened. His now had a girlfriend now for two years and Iv always respected that but I sense there’s still bit of flirting going on between me and him, you can kind of tell if you was in a room with us there’s a spark there, even family members have said this to both of us actually and we’ve just kind of giggled it off. I think obviously that is pretty harmless as we’re not sleeping together or anything like that. We never text each other either before anyone thinks we flirt over text or anything, only thing we’ve ever text each other before was merry xmas to you & the family thats it. Anyways a few weeks ago he said to me when we was drinking at a family party that he fancied me and that one day he’d love to be with me but the timing is not right and he said I want to mature more too I was really shocked this came out of his mouth I was like wow ok I can’t believe this has happened and I said back of course I fancy you too but yes of course I know you have a girlfriend & you are also my brothers friend so I don’t want to upset anyone either.
He tried adding me on Instagram the day after this happened but I declined it as i didn’t want to upset myself with seeing images of him and his girlfriend looking all loving and also him seeing what I am up to either eg if I were ever to meet someone lovely. We do have each other on tiktok where we both post stupid videos and we’ve liked each other videos. Like I feel pretty sad I’m not gonna lie because really now I feel we’re gonna have to both avoid each other. Apart of me kind of wishes in the future I hope we can get the chance to know each other better on a romantic level to see what may happen obviously if a 3rd party wasn’t involved and another part of me is like come on move on now and leave it be. What’s your thoughts on this?