“I was supposed to go out with a friend but canceled last minute since I was just too tired. That was two days ago, since then she has been calling me constantly, and texting too. I have let her know I am fine, just tired. She still won’t stop calling…”
Firstly, I hope you are not feeling guilty about the canceled plans. Although it may be an inconvenience, you are completely within your rights to cancel a social engagement. We all have times when we are too tired, too busy, or too whatever not to want to commit to an evening of socializing. How we deal with that (i.e. do we keep our appointment) depends on the people, the activity, and probably a whole host of other circumstances. Whatever your choice, it is yours.
When people give a completely unexpected and overly emotional response to something simple, it often helps me to take a step back and see what is going on underneath the surface.
Ask yourself the following: why is your friend overreacting? Phone bombing you over canceled plans definitely counts as an overreaction, especially because—like you say—you have let her know you are okay and there is no need to worry. To me, this sounds more like manipulation to pressure you to change your mind, or maybe some form of emotional blackmail intended to make you feel guilty about your decision to cancel.
Remember that you are in charge of your boundaries. If you do not feel like talking to your friend right now, that is fine. It would be different if you just didn’t show up, or made her worry. But you canceled and assured her you were fine. That should be enough for any healthy adult.
Perhaps it is best to just switch your phone or ringer off. That way you do not get stressed out when it rings or beeps.
Do something relaxing and restful to take your mind off things. It can be anything. I love creating a little home spa while my partner’s go-to activity is playing some video games. We are all wired differently, and you will know best what helps you release negative emotions.
Decide when and how you want to address this behavior with your friend. If they are toxic, they may want to just pretend it never happened. But you will want to make it clear that it was inappropriate. On the other hand, if they blow it out of proportion and want to start a confrontation with you, your choice could simply be to say that you switched off your ringer and went to bed.