Apologies if this is the wrong place to post

So basically I am seeing my friend soon after a week or so of not seeing him, so I sent a message saying I was looking forward to it and he responded with a thumbs up, which now I type this out doesn't sound like a big deal at all, however after not hearing anything after that I just felt like he hated me and I'm forcing myself on him and he doesn't really want to see me at all. I guess my subconscious wanted some sort of reciprocation? 
I don't know why I felt this way, as just a few minutes before we'd made another plan too which he seems happy about. I went into a real panic and ended up self harming over it! I know this is ridiculous and obsessive and I wish I wasn't like this and I am desperate to change, but have real trouble with responding reasonably to situations like this. I hate how I'm totally lucid now and can see how dumb it is to be so sad over something which ultimately probably had no thought behind it whatsoever
Have been very on edge recently anyway but even so I feel like such an idiot to blow up over such a small thing, does anyone know some advice on how to cope with this?  Thank you

tl;dr, Self harmed over an emoji and want to not do that lmao