[HELP] Should I tell my mom?

Problem/Goal: Okay, so I'm a girl. 17 years old. One night, when I was 11 years old, my mom had a business trip, so she had to leave our family for a couple of days. When I was tucking myself in bed (my family and I shared one bed at that time), my dad suddenly raised my shirt and slowly slipped his hands in while I was "sleeping" (because I was facing the opposite direction from him). Ever since then, he would constantly do it every night when I "fall asleep", even when my mom was sleeping in the same bed. I got so sick of it every night that it made me have insomnia. So I finally started sleeping in my own room, even though my mom doesn't like it when I do so because she knows I'm just going to spend the whole night using my phone anyway. When I transferred to my room one night, somebody suddenly opened the door, and I quickly tried to pretend to be asleep. Turns out it was my dad again. But this time, he didn't touch me; rather, he took my first kiss. He reeked of alcohol. After he kissed me, he went back to the living room, and I couldn't help but burst into tears, trying to be as silent as possible.

And now, I'm 17 years old, still unsure whether I should tell my mom or not. I mean, he stopped it already, a year ago, I think. But I'm afraid that if I tell her, she might not believe me, and my dad might do some stupid shit like shoot me or something (because he's a police officer). And if my mom does believe me, we might have financial problems, and our family will never go back to the way it was again. I don't want to cause any more problems, especially since I'm graduating from senior high soon, and I still have a lot of college entrance exams that I should take (I have an exam this Sunday).

What should I do? I genuinely do not know what to do anymore. I really need advice. And I'm sorry for the awful grammar btw.