If you legitimately care for your boyfriend then you need to do what is best for him.

The best thing you can do for him right now is to end your relationship with him, tell him what you did and why you are breaking up with him if you think that will hurt him less than simply ending the relationship, but you must end it.

You can try and rationalize this (as I suspect you will) and construct an inner narrative in your mind where you aren't the bad guy, where this is just because you are depressed, or anxious, or that you have low self esteem but all of this doesn't matter - plenty of people have far worse problems than you have and don't do betray the people they love.

Being in pain is a sorry fucking excuse for hurting other people, people are in such terrible situations all over the planet at this very moment and they don't betray their partners like you did.. stop making excuses, stop and have a serious look at yourself.. is this who you want to be?

Stop being a coward, stop being a child, grow up and do what is best for the man you love and leave him so that he can find someone who is trustworthy and won't betray him.

Then do some serious soul searching, find out what kind of person you are right now and what kind of person you want to be in this life before you die, if you decide that you want to be a loving, caring, faithful partner to the next person you fall in love with then become that person and use this entire experience and the pain it will inflict upon you as a lesson so that you never become the person you are right now ever again.

If you continue your relationship with him then you are a scumbag, that's all there really is to it, the only reason he would stay with you is out of desperation and it will only prolong his suffering.