My [31F] boyfriend's [32M] brother [22M] upset me by talking about my mom's death, and my boyfriend is taking his side.

This Thanksgiving is the first time I met my boyfriend, Jake's, family. We've been together almost a year and are talking about moving in together, so it seemed like it was time.
In advance of our trip, I asked Jake to tell his family about my family. My mom was murdered when I was in my early teens. As she was a single mother, with no real family, I was bounced around to foster homes until finding a nice family to live with for the last few years of my teens. I am still in touch with that family, but not in a 'they're my family' way, just a 'send a Holiday card' kind of way. My mother's murder was obviously an extremely traumatic experience for me, and it was a somewhat notorious case in the area I grew up in, to the point where I occasionally get tracked down by the websleuths crowd or other gawkers and get harassed.
I asked my boyfriend to tell his family about this just to avoid any awkward questions about my family over dinner, because I've been put on the spot before at events and didn't really know what to say when pressed besides, 'My mom was murdered and I have no family! Pass the peas!' which makes things very awkward and makes me feel like crap. Also, my name is very similar to my mom's name, so sometimes when I meet strangers they will make a connection and be like, 'Like that lady who got murdered!' (For example, if my mom's name was Elizabeth Shoemaker, mine would be Ellie Shoemaker) not thinking I'm actually related to her.
So, the actual problem. The plan was to arrive on Thanksgiving for dinner and then stay the weekend. Jake and I got there, ate dinner with the family, helped with dishes, and were having an overall great time. His parents were lovely and didn't bring up anything awkward. I was finally getting comfortable when his parents decided to go see a movie with some friends in the evening, and Jake went with. I decided to stay behind because I had a headache. I was left alone in the house with the dogs and with his younger brother Chris, who just graduated college and moved back home.
Chris and I hadn't really interacted during dinner since we weren't sitting near each other, but he seemed like a nice enough kid. I didn't really expect to interact with him much, as I was lying on the bed in the guest room with a headache, but about five minutes after the door closed, Chris appeared in the doorway with the opener, "Jake told me about your mom. Were you there when it happened???" and started, believe it or not, peppering me with graphic questions about THE MURDER OF MY MOTHER.
I was stunned and didn't know how to respond, so I repeated, "I don't want to talk about this' and he finally said, 'Sorry' and left. I sat on the bed for awhile not really knowing how to react but feeling general unease, shock, and the mild feeling of panic I get when people mention my mom's death when I haven't mentally prepared to talk about it. About 15 minutes later, he was back, having Googled it, and excitedly started TELLING me what he read, how he found a forum where people have alternate theories, what did I think, etc. I again told him I didn't want to talk about this, and at this point closed and locked the door and stayed there until Jake got home.
When Jake got home, I was visibly extremely upset, and told him about my interaction with Chris. I told him that I'd prefer to go home; that he didn't have to come back with me, that I'd get a rental car and drive home, but that I didn't want to stay in the house with Chris. I expected some support (and genuinely didn't expect him to interrupt his holiday for me!), but he immediately told me that I was overreacting, that kids now have a morbid sense of humor, that Chris is a good kid, that it probably wasn't as creepy as I said, that he's just a kid, blah blah blah. I was shocked because I felt like Chris clearly crossed a line, and my gut was telling me that he was not a safe person for me to be around (not physically but I really did not want to spend the weekend with someone who was going to keep picking the scabs of the worst trauma of my life).
I ended up taking the car (which is actually my car) because Jake said his parents would drive him home. His parents were already in bed, so I left them a note thanking them and saying I had to leave suddenly because I wasn't feeling well. I drove four hours back home alone and stayed with a close friend all weekend. Jake's texts to me were short all weekend, and when he got back to his apartment he didn't come over or invite me over, and said that he was 'still angry' about the way I acted toward his family.
At this point I don't know what to do. I know I didn't overreact. 22 years old is young comparatively, but a 22 year old is not ACTUALLY a kid. He definitely seemed to be enjoying how uncomfortable he was making me, and I have had enough contact with 'websleuths' type people or people who are 'fans' of murders to know that he was being creepy and invasive. The fact that Jake is mad at me for all this makes me want to break up with him, and that's the part where I can't tell if I'm overreacting. Should I expect him to have my back over his creepy brother's? Should I bother trying to make him understand this? Can we have a relationship if I don't want to be around his family?
I'm sorry if this is unclear or disjointed, I am paranoid about accidentally giving identifying details so I may have messed some things up.

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TL;DR: My boyfriend's little brother cornered me twice to ask me invasive questions about my mom's murder. My boyfriend thinks I overreacted by removing myself from the situation.


Source.

@Sparky: One thing that you need owed an apolagy over is how they brought up your dead mother. A relashionship takes strengh to sow and set it streight. With an by the sounds of it. Trust your instink if its his pants not the cair watch it. Hoap the advice somewhat helped. Most people argue then chill which is a miss match calm and loving as well as respectful is out there just hard to find Cheers an all the best