I was reluctant to get a bidet because I couldn't hook it up to a warm water line, and was pleasantly surprised when I realized buttholes really aren't that temperature sensitive. Even in the dead of winter, cold well water shot straight up the butthole doesn't feel cold or shocking at all. Probably impossible to believe unless you try it yourself.
Also, don't be a monster and dry your butthole with a towel. Just use a little bit of toilet paper so if you're still dirty, it's okay. It's not like your whole rear-end gets soaked, it's a very thin steam of water that targets just your butthole, with maybe a tiny bit of spray on the surrounding area
Distraction is the best coping method. I listen to audiobooks instead of trying to sleep and I fall asleep faster without the constant stream of internal anxious chatter