Crazy ex or crazy me?

Andrea
Hey! 
Okay so I really really would love to hear some opinions here. I'm going a little crazy.
My boyfriend an I are already over a year together and he and his ex broke up about 2 years ago. 
They're still friends on Facebook which doesn't bother me at all (since I'm Facebook friends with my ex too) And I'm really not jealous or even worried because I know how much my boyfriend loves me.
The thing is his ex girlfriend started liking pictures that i posted of my boyfriend and I together. First I thought it was weird but I didn't put much thought into it.. 
lately though it's kinda been getting out of control. She's liking every single photo I post of us and she's even going into my Instagram account (she doesn't even follow me) and she's liking my pictures there with him too! 
Now maybe I'm just thinking too much and this means nothing 
But do you think she's still not over him? Or maybe she just wants to be a bitch and contantky remind me she was there first? Maybe she doesn't want my boyfriend to forget her? I mean what does she want?! WHY is she doing this????
It's driving me CRAAAAZYYYY
(Her and i are not friends on Facebook i dont even know her and I don't want to block her because I think that's immature)