How to deal with seeing someone I have feelings for everyday but can’t have

I work in a really close/friendly start-up environment. I’m talking about dinners/brewery hang outs at least once a week, group chats, & eating lunch in the break room together everyday. I really liked that aspect, especially because I’m in my early 20s and I don’t have a lot of friends in the area. I got really close with one of my guy coworkers (27M) and he started texting me everyday for a month and flirting with me in the office. He eventually asked me out and I was so excited, I’ve had a crush on him for months. We went out on like 8 amazing dates in the span of 1 month and hooked up twice. I left for vacation (I went to Europe, but he texted me basically everyday asking how my day was!) and then when I came back 3 weeks later, I noticed he started distancing himself from me/texting me less.

Eventually, we talked in person and he told me that he’s not ready for a serious relationship right now. He said his mental health got really bad when I left for various reasons – his grandmother is sick, his best friend moved away, and he has intimacy issues. When we slept together, he had erectile dysfunction both times & said he’s been dealing with this issue for the past two years. I told him that didn’t matter to me, but he said it’s affecting his mental health/ruining his self-esteem because he doesn’t feel like he can be good in bed for me.

He said that he’s really sorry & the door is still open on his end if things get better – that he really likes me a lot and I did nothing wrong.

This was in October & I still try to act the same at work/talk/hang out in groups and we still act normal in person. But deep down, this really stings and I go home a lot crying because I either A) Miss him so much – being intimate with him or our dates B) I miss his friendship. I feel like I can’t text or talk to him the same way I used to. C) If I do act sort of flirty or the way I used to, I feel like an idiot after.
I just don’t know what to do anymore. When I distance myself, I feel sad and miss him. When I spend time with him, I feel like an idiot because it will just make moving on even harder. When I try to date or move on, I keep thinking about him & I haven’t found someone else that I like yet. I also don’t want to seem desperate and I’m not the type to do rebounds really. I tried dating apps since then but I’ve just gone on like 4 shitty dates so far that went nowhere. I do all the things I’m supposed to with a break up – I hang out with friends any chance I get, I try to delve into hobbies, I even tried applying to new jobs. But still, even when I’m busy or trying to switch jobs, he’s all I think about. I fell for him pretty hard.

TLDR – I fell for my coworker & we dated, but we broke up. Now I have to see him everyday and I still have feelings for him. Any advice on how to cope (besides changing jobs, since I already have tried that/kind of stuck for now). And I know they say don’t dip your pen in company ink, but its already too late.