I Am Insecure About Myself

My grandma (with whom I live) treated me a bit badly. Not physically or insulting me, but basically once more woke in a bad mood and lashed out at me over nothing. Even her goodmorning, literaly her first words of the day to me, she said like she wanted to hit me. This is something that I've been dealing with my whole life, first with my mom, now with her.
Most people don't get why it bothers me so much, it looks like a minor thing at first, after all everyone gets moody sometimes right?
What I need people to try to understand is that this isn't once in a while, it's a constant thing that I've dealt with for years, and after a while it builds up.

But anyway that's not the point of the story.

I wanted to vent to someone and get some support. But my neither my friends or my boyfriend were avaible. I figured I would just tell my boyfriend when he woke up in a few hours. But I just realized that imediately I imagined how that would go and what I imagined was that my boyfriend would start defending my grandma (that she's old, that she's probably not feeling well, oh poor thing, etc). It got me thinking why is my automatic reaction to expect people to not take my side? has he done that before and I haven't realized? or is just my paranoid head and low esteem putting these thoughts in my head?

update: my boyfriend did indeed take my grandma's side... basically said that her age excuses her behaviour.
And after I vented a bit more imediately said he had to leave. It felt like he was running away to be honest. I felt incredibly unsupported too and like I can't count on him at all.