Hey there, I'm sorry you are going through a difficult time right now. I can be very hard to hid how you really feel, especially when you are feeling really down about your life.
You are only a young girl so you do have many more years left to have a boyfriend and get into a serious relationship. We don't need a boyfriend to make us happy. You should start to focus on yourself and your well being more right now than anything else.
We all have our ups and downs in life but when it starts to effect certain aspects of our lives, there is a problem there. You aren't alone, you do have your friends even if you don't want to hang out with them anymore. Can you think of any reasons why you'd rather not be around people who do really care about you? Why aren't you bothered to try and mend your friendships? You shouldn't give up on friendships you have probably had for many years and worked for. Friends are there to support you when you really need it and you could do with having them there.
Speak to your closest friends, or even that boy was in your class. Just because you are now finished school, doesn't mean you just give up on the friends from school you made or the people you spoke too. I, often see people from my class and we still speak and catch up. Get in touch with him, become closer friends have have someone you can speak too when you need them. Even if it means you speak to your father or brother. Either way, you could do with someone to support you and help you through this.
When you are in a rut like this, you shouldn't need to suffer in silence. I suffered the hard way by keeping it to myself when I was in a situation like this. If I have learned anything, it's that I should have spoke out and had someone to support me when I was dealing with this.
Don't even change who you are. We all have our own personalities and that is what makes us who we are. Even if you are usually cheery, upbeat, hyper; you can't always be like that. You are just having a difficult time and you will get over this with the help of your friends in real life and your friends here.
I wish you the best of luck and hope I have helped. You can message me if you need someone to talk to. Good luck.