Hi I'm new to this site

I'm feeling really anxious my lil sis goes to kindy next door to where we live.
mums at work. I just got a call from them to come and pick her up because she said she wasnt feeling well.
she had gastro twodays ago. and now two more kids have come down with it.
I'm freaking out because I always go into the kindy to drop her off and settle her. and touch things
I don't want the bug

I was alright when she was sick though i could't stay in the room for long.
I feel like a horrible big sister.
but I just cant deal with it.

I'm trying really hard to help my mother out but I just can't seem to stop the thoughts and none of the
exercise I was given seem to work. My anxiety is through the roof and I keep snapping at everyone I hate it.
any advice?
I'm on lexapro but I don't think it's working.