Do I tell him or no?

My boyfriend's sister acted very volitally aggressive last night and caused me to have a ptsd episode. She wasn't in the room and he was sound asleep so he missed her yelling at her friend and then arguing for 20 mins about how she didn't want me in the house, throw something, and then bang on the door and yell about how he drove her out and that they needed to talk about house rules. All I did was go inside and go right to his room. I didn't engage her or get into her personal space. He had invited me over but didn't tell her because he didn't feel like he had to.

I'm just not sure if I should say something to him in the hopes that it will help me not have another ptsd episode. I don't want to cause any fighting and I don't want him to feel defensive of his sister, whom I have nothing against save for her actions last night. I just feel very uncomfortable and not safe occupying the same space as hers for the time being.

Thoughts?