I notice that you are new to PC, welcome! I hope you find your time here to be of benefit!

People make mistakes. You recognize that what you did was wrong, and feel remorseful about it. That matters a lot. Also, although kissing someone else definitely still counts as cheating, it's (to me) not as bad as sleeping with another person. You stopped the situation before it could get that far, and that's good! Please don't be so hard on yourself. Just don't do anything like this again, and over time you will regain your boyfriend's trust. Good luck.