Step son tying to hurt my newborn

Olivia • Mommy to a baby boy 💙

I’m so bothered by this idk what to do. I have a 6 week old baby with my boyfriend. We’ve been together almost 5 years and he also has a son from a previous relationship who’s 10. His son is so sweet and so excited about the baby. We have his son every other weekend, or whenever he wants to come over. It’s Friday, so we just picked his son up and we’re driving home (about 30 minutes down the freeway). My boyfriends son obviously didn’t notice the little mirror I had that allowed me to see the baby. We were driving and the baby was asleep. He was trying to wake him up by shaking his hands and arms but I didn’t say anything. Then he starts shaking his head and pulling his eyes open. Putting his finger between his eyes and moving it around very aggressively. I tried not to freak but got a little feisty and said I know you wouldn’t like that if you were sleeping. He caught an attitude and “fell asleep” in the back seat. I forgot about it till I dropped them off at home then texted my boyfriend about it once I got to my moms. I’m so bothered idk how to handle it. I feel like I can’t trust him at all and if I’m being honest I don’t even want him around right now. I’d rather take him back to his moms. He was being very rough with my baby. He’s usually so sweet I would have never imagined he’d do that. Any advice? Really frustrated 😞