I am going to suggest you treat it like an addiction and get help. You have already made a first step by coming here and we will do all that we can to help you, but you need to see someone who can back up their advice with verbal and physical interaction. Eye contact and having someone hold your hand can help reinforce your resolve to move forward.
You know what you need to do. It isn't going to be easy, but you do have support available. You can also become your own best form of support if you give yourself a chance.
Don't expect everything to be 'fixed' overnight. It will take time and you will think about backsliding and contacting him. However, you will survive and make it through this if you give yourself support.
There is a method for moving forward from a break up called No Contact. It is a 'cold turkey' way of letting go. Tell him that you are letting him, the relationship and everything else go. Stop all contact with him. Do not accept any contact from him. Delete messages, his phone number, de-friend him on any social websites, send emails to the spam folder and do not look at them, etc. If you can think of a way you might be tempted to contact him, block it. It may hurt, but it will help you keep confusion down to a minimum.
At the same time, get involved in your life. Catch up with friends and family you might have let go while seeing him. Hobbies, volunteering, continuing education classes, clubs, working out, etc. can give you ways to keep your mind and body occupied so you are less likely to try to contact him.