I want to let my boyfriend think he won
Are you going to put this behind you now?
I'm going to let him think he won, but I will eventually show him what I am really capable of.
You should be honest with your boyfriend, and not so eager to get revenge. Making them think they won won't help the situation, and delaying your payback could just make things worse.
What else should I do if I don't let him think he won? This would never end.
If your boyfriend is really stubborn about something that you disagree with, the solution isn't to be deceitful or to seek revenge. You should let him know that you are willing to compromise for his sake, even though you are still not satisfied. This is honest, and it will probably cause him to soften up in the future.