How do you deal with being forced to socialize with big groups?

I would ask your Grandmother for some space if it's making you uncomfortable. I know she means well, but making it mandatory sounds like it's really stressful for you.

The only advice I can give other than asking her to not pressure you with this every day is to try to focus on something that distracts you from yourself. Can you bring something like a game that everyone can play so you don't feel the focus is on you? If you're going out of the house, personally I find wearing sunglasses can help me feel like I have something to hide behind.

I hope that helped!