My [M27] family wants me to break up with my girlfriend [F22] after how she responded to my brother’s [M22] prank

Hi reddit! Long time lurker, first time poster. I know how the title sounds, but i could honestly use some outside perspective since anyone else I could ask is biased towards the situation. I have been dating my girlfriend, Lola for about two years now, and overall things have been great. My brother Ian has always been pretty weird whenever she comes up or is around. Ian and I are very close, talking to each other daily, but the conversation will usually change gears right as I start talking about anything Lola related. I thought maybe he was jealous of the time I was spending with her or maybe a little crush on her. Still, whenever we'd get together, he'd make comments about our age gap, poke fun at me for simping, and joke about her sleep disorder. Ian's always enjoyed a good prank, either pranking or being pranked, he loves to laugh and I genuinely believe that when he goes to prank people, he means it in a way to share the laughter. When he's tried to pull little pranks on Lola though, he does things that he figured out triggers her disorder, like making sudden loud sounds, jumping out to scare her, and one time I caught him before he was going to do the shaving cream sleep bit while she was taking a nap in the guest room. I warned him in more detail then that he shouldn't mess with her while she's sleeping, as interrupting her regulated cycles isn't good for her, and AT THE ABSOLUTE BEST she's the WORST kind of cranky when she's woken up. Ian looked like he understood and I thought that was that. I threw a NYE party a few days ago and invited Ian and a bunch of mine and Lola's friends. Everyone was having a good time, my watch went off with the alarm that we set up for Lola to take a nap, she went off with a sleepy smile, I kept partying. A while later we all heard a scream, followed soon after by cussing and something breaking. I panicked as it was from my room where Lola was and I ran through nearly kicking the door down to find she shoved someone down and was yelling at them. I looked to see who it was and saw a spider mask that I unfortunately recognized as Ian's from years ago. I saw him scrambling to get away, but she only stopped when three of her friends pushed past me to pull her up and check her before she ultimately passed out in their arms. Ian scrambled off the floor and ripped the mask off, revealing the work she'd managed to do in the time it took us to react. He started bawling telling me that she was insane and abusive, that he only wanted to make sure she wasn't going to sleep through the ball drop. At this point everyone started yelling. Ian looked terrified and kept repeating that she was crazy and that I shouldn't be with someone who could do this to her bf's brother. Some of my guys were yelling that if she did it to him she could do it to me. All of her friends were screaming about how he should know to leave a sleeping girl alone and how it was creepy. Ian ended up calling our mom to tell him that Lola hurt him and she's furious, Lola's friends ended up carrying her out against my protests, and my friends were nearly split down the middle. I remember standing there while everyone argued while the ball dropped, my mother calling me for the tenth time, and Lola finally texting me that she needs space to think. Since then we've lightly texted, she's expressed that she can't shake her fear of what happened, but she still hasn't told me from her side WHAT happened. Ian and my mom are trying to convince me to break up with her, and chastising me for not helping or standing up for my brother when he was being assaulted, also demanding an apology for not playing my part as an older brother. Ian has facetimed a few other family members and now my aunt, who paid for both our colleges and the house my mom and brother live in and helped me get my apartment, is taking the three hour drive up to make sure her boys are okay, which is stressing me out even more. On one hand, i know family is family and I should do what I can to stand up for the people who helped raise me and become the person I am. On the other hand, Lola is my girlfriend, I adore her, I love her, I feel like I should be there to protect her. I don't want to push her boundaries but not talking to her is a different kind of hurt. Ian is convinced that he was doing a well intentioned prank and was wrongfully punished for wanting to make sure everyone was enjoying themselves. I don't know if i believe that, but I've known Ian for 22 years, growing up we were inseparable. I don't want to doubt him just because love may be blinding me. How do I approach the situation with Lola How can I convince my family that Lola isn't a threat, she's honestly the most sweet and caring person, she just can't be woken up and part of me feels like she was pushed to that point.