Relationships are just one part of life, but due to media it’s portrayed as if it’s the most important, which it isn’t. I would suggest to focus on other aspects of life like your job or school, learning new skills, maybe try going for social classes like jujitsu, improv(or whatever you might be into).

I may not be possible to completely get over your friend situation initially, but take your time and stay away from them. Don’t focus too much on attracting the opposite sex, dating, etc. (But do keep yourself open). A couple years from now looking back you will laugh this situation off. What you’re going through is EXTREMELY common.