I dont think you've done anything wrong. Your girlfriend should not be taking up all your time when you're away with your family. Especially during a difficult time. It's so controlling and selfish.
This reminds me of something my ex did the first week of us dating. It's on a much lower scale. And honestly I wish I had pieced it all together right then and there. I was inexperienced with relationships and only 19. My mother's father, who I never met, passed away. I did not know him but I attended both wakes and the funeral for my mother. There were no more than a dozen people so she needed me. Regardless, she needed me even still. I told my boyfriend about the funeral. He then guilted me. "When am I going to see my new girlfriend..." he tried to get me to ditch a wake which I almost did. I'm glad I didn't cave.
I dont know about your girlfriend but it can be a sign that she is insensitive, selfish and detached. Because it didn't get better for me with my ex. Fast forward 4 years, he would rather drink and party at his house when his parents were away than comfort his crying girlfriend who lost her 14 year old dog (I have PTSD over my dog because she died traumatically). He did not even invite me to his party. Not that its any better but he's not an alcoholic, so it wasn't even addiction problems. I actually almost dumped him over this. I remember what I said to him then and you should consider this thought. "If you're not here for me for my dying (dog/grandma) WILL you be there for me when it's even worst?"
Fast forward another two years, my ex was annoyed I wasn't talking to him when my mother and I went out of state for mom's uncle's funeral. When I tried calling he was playing League of Legends and later expected me to be up for talking after the game... at 1AM...
I'm projecting I guess but don't be like me and spend 7 and a half years with someone who is so self-centered over something as emotionally taxing as grieving loved ones and spending time with family. It's possible she never had those kinds of relationships before so shes jealous and insecure. But it doesn't make it okay. If anything, talk to her about it. Ask what was up with her behavior. But she's 28 or 29. I kinda doubt she will change her personality. My ex was 23 when we started dating and 30 when we broke up.