Are my parents over reacting with grounding me for 45 days?

So here’s what happened: I (17F), my boyfriend (19M), and my best friend (17F) all stayed the night at my house with my parents’ permission. We were hanging out and eventually decided to go to sleep. My sister had fallen asleep on the couch, and my boyfriend didn’t feel comfortable sleeping in my sister’s room. I didn’t feel comfortable with him and my best friend sharing a bed, so we thought about it and decided that all three of us would share my bed. We didn’t think it would be a big deal since my best friend was also there. Plus, we kept the door open all night, and my parents’ door—right across the hall from mine—was also open.

The next morning, my mom came in to wake me and my best friend up. She saw my boyfriend in the bed with us and completely freaked out. She grounded me for 45 days and made me take him home immediately. I’m allowed to keep my electronics because I need them for school (I’m homeschooled), but I’m not allowed to do anything or go anywhere except work until March 19. I’m also not allowed to go out for Valentine’s Day, even though I’ve been talking about how excited I was for it for weeks since it’s my first relationship during Valentine’s Day.

So, am I being unreasonable and actually deserve to be grounded for this long, or are my parents overreacting?

Edit: i want to make a few things clear, my sister is 11 and the type of person who once she is woken up she won’t go back to sleep, my and my best friend didn’t sleep in my sisters room because she has a twin bed, my boyfriend was uncomfortable sleeping in my sisters room, he didn’t sleep on the floor because the previous owners of my house had dogs so my carpet smells like pee

Edit 2: for everyone worried about age my boyfriend turned 19 in November I turn 18 April and the legal age of consent in my state is 16