How to be single?

You wear what you want to wear with worrying if he likes the way you look or approves of what you are wearing. Ditto for makeup/no makeup and hair styles/color.

Watch the shows you want to watch. Ditto music. Ditto what you eat.

You go where you want to go, do what you want to want to do. Etc.

In short, you live your life the way you want to enjoy it. And when you do that, you will realize you are too busy enjoying yourself to realize uou are single.

There are books teaches how to be single and be happy. I like to be alone most of the time. I can find things to do when I am alone. This is good time to know more about yourself. What satifide you? Do you need to talk all the time? why? You can find someone to chat with online and on the phone. Do you need touch? There are groups on Meetup.com that exchange massages and cuddle. You can talk to a councelor. See what the councelor think.

I think what Peter says about massages is a great idea! Going to a massage therapist is great for relaxing and it might even help your sexual problem. Stimulating that large vein that runs down your spine to your anus is a great way to release stress and hormone flow as well as blood flow to those lower regions.
Also many massage therapists are chatty and will talk with you while you're getting a massage. You may even make a girlfriend.
Another great idea is seeing a hairdresser regularly. You will feel better about your looks while getting some TLC. I love getting my hair washed by someone else, and again, it's someone to talk to and look forward to seeing when you are lonely.
I'm not sure what sort of problem you have down there, but I've had several and getting massages and doing yoga helped alot because it helped me learn to relax and not be so tense. Sex quit being so painful. Eating a clean diet, exercise, and getting your hormones balanced will help alot too.
Then when you are ready get back on the dating scene. I was still a virgin when I was your age, so a 19 year old not being single is just laughable and ridiculous to me. That's way too young to be getting married or worrying about children.

The right one for you will accept you for who you are-limitations and faults and all. Get involved with crafts and hobbies that interests you and you will meet others with your same interests

Your feeling this way because you have never known how to be happy or deal with issues on your own. You have ALWAYS had someone to run to..,. to help you. You need to learn how to be happy alone and to be independent. I have gone through something Very similar to you. and at 17 years old, I won a public speaking competition at Harvard University, traveld the world and have helped people on a global scale. I have a step by step process that I have come up with that helps people directly with working on being happy alone and dealing with things on your own. Its been used in places such as Brazil, Turkey and even Pakistan!! if you ever need any advice or someone to talk to, I am here. I know EXACTLY how to help.

Well firstly it sounds like you made the correct decision leaving your boyfriend. It wouldn't have ended well if his personality had turned and it was impacting on your mental health. As for being single, it can be a good thing, you have a lot of freedom that is not available in a relationship. I have been single and alone for the vast majority of my life. And yes I think being permanently single can be an issue, especially if you want a relationship. But whilst you are single work on yourself, learn things about yourself, try new things like hobbies and experiences etc. You are only 19, that's really young! You have plenty of time to find somebody.

Coping mechanisms are great. Everybody needs a release. Mine was exercise, but you can find anything. You just need to find something you can enjoy and that distracts you, and make sure it is both legal and healthy.

Why do you feel that you have no hope of getting another relationship? I assume it is something to do with the physical issue you mention? I don't need details but that doesn't disqualify you from relationships. It may narrow options, but there will still be people there. Without knowing what it is it's hard to say, but there is a possibility you are overthinking it and building it up to be more of an issue that it is?

But for now enjoy university, studying can also be a good distraction and helps you get a good grade. Your uni may offer counseling, mine did. Hope you manage to figure things out.