Huge cut on my “area” lol

So me and my boyfriend had sex last night & this morning and I started bleeding really bad. I though he was just being too rough, but when I was taking a shower this morning it was very tender on the inner part of one of my lips down there. Sorry for the TMI but hey we’re all girls here. So I looked and I have a huge cut. I’m confused how it happened because I would’ve felt it when I was shaving because it’s THAT bad. And it doesn’t bother me all the time, just when I touch that area. Can someone give me some insight lol