Beyond pissed. Please help calm my nerves

So I was online to someone and here’s the convo and why I’m pissed

Them: when was the last time you were truly scared?

Me: when my daughter was 6 days old and stopped breathing

Them: LOL

Me: That’s not a laughing matter and seriously how rude

Them: did IT die (yes they called my daughter an it)

Me: my daughter was dying it’s not funny, she’s okay now but near death experience isn’t funny.

I then blocked them because I was about to say shot that would have been horrible but I’m beyond pissed and I can’t seem to calm down