Advice on fighting?

So this kid at my school who's like lowkey my opp but also my friend? He's fake as shit but anyways, he found out who the girl I have a crush on is and started telling evb that it's her. I'm not gonna let his ass slide with this shit so how do i fight without hurting myself? I know to punch with the front 2 knuckles btw so like any other advice? btw im trans and a lesbian if thats important bc he is kinda homophobic so idk.

If yall need to know like the laws of my area i live in chicago.