Toddler loves grandma's house a bit too much?

So my toddler (soon to be 3, F) had her first sleepover at grandma's house. It's the first time she slept anywhere else but home.

I expected her to miss me a little bit (I'm a SAHM and with her all the time), but no, she violently refused me when I came to pick her up.

I had to carry her away, screaming and crying about how she only wants grandma, which continued for another hour and a half. She's speaking about grandma all the time ever since. She doesn't want to be home, she wants to be at grandma's house.

I am devastated and heartbroken. I recently found out that my daughter's dad has been cheating on me with his student for most of our relationship and I feel so worthless. I feel like I am not, was not and will not ever be good enough for eighter of them.

Has anyone been through this? How did you get over it?