Thank you @PuffinSock for the kind words too
It makes me feel a little better to know you don't all think I'm overreacting by being so sad about it. I have to work in a little while and I'm just so demotivated... keep dwelling on how cute and fun our dates were and how I was so blindsided by the fact there most likely won't be any more of them... feeling so lonely rn.
I think your idea of what to say next time he contacts is a good one Puffin. You deserve way way more than to be someone's fallback. Seeing photos of an ex with someone new always dredges up a myriad of feelings but it sounds like it's given you the power you needed at the moment 
@herbsmokedchicken I'm sorry you're feeling so down too
"Flat" perfectly describes how I've been feeling too... It's so awful when you're so upset at work that you can't really hide it properly, the other day someone told me (in a nice, concerned way not as an insult lol) that I looked "really tired, totally drained" and it was someone who doesn't know about the situation (I've only really told two of my favourite coworkers about it) so I just kind of said I hadn't been sleeping well... which, well, I haven't, but it's more complex than that!
@Joules8719 I've been feeling those waves of sickness/nausea too, usually when I try to lie down and sleep and then just start overthinking.
Ahhhhh I miss his stupid face and all the potential we had for such a good thing! I actually feel like I'm feeling worse about it day by day instead of better. Maybe it's because of the darker nights rolling in making me feel more lonely and the thought of things coming up (his birthday, my birthday, Christmas, the Christmas markets, the local funfair etc) that I'd hoped we could share together and now it seems so unlikely.