I'm going to cancel plans on my friend with bpd last minute because I woke up feeling really sick
Are you worried that your friend will get upset?
Yes, I feel really bad doing this to her.
It's normal to feel bad when you cancel plans. But it's really best to stay away from other people when you're feeling sick. You should make a plan to meet when you're feeling better again.
That sounds like a good idea. It's no shame having compassion and understanding for friends with mental illnesses.
If you are feeling sick then there is nothing for you to feel sorry about. While the situation is unfortunate, I am sure your friend will understand your reasoning! In addition to that, when you are feeling better you can still plan to spend time together.