I miss my ex-boyfriend... Now that we aren't together

So I broke up with my 20 year old boyfriend in the beginning of August. As a 17 year old girl, I have more priorities than having to deal with boys. I had lost interest in seeing him really, one reason being bad anxiety and another was because I found him on tinder after he said he had deleted it (I have a tinder for the pourposes of drawing the funniest bios and profiles I can find). He was also seeing a girl in my grade before we started dating, and I felt terrible for doing that to the girl. 
I forgot at the time we dated that to be happy with someone else I have to be happy with myself first, and I'm struggling with depression and anxiety and really just wanted him to be happy. We dated for a few months however and I broke up with him over text, and we haven't talked much since. I went on a few dates with another guy, and really enjoyed it, but I found myself missing my ex more and more. Should I talk to him again? Also, how should I reach out to him? His birthday is in 5 days. 
Also, I do not enjoy kissing at all. With him at least.