I regret that I cheated on him and miss him.
Did you end up telling anyone about this?
I did not think of telling anyone.
There is never a valid reason for cheating on someone. If you find yourself wanting to cheat on someone then you should think about just leaving them instead.
I don't know, I had a feeling we were not going to work out.
Just because you think your relationship is failing, doesn't mean you should cheat on them. How would your boyfriend feel that you did this to him? It's good you are regretful, so you can learn to treat your next relationship a lot better.