MIL wont accept my mental health.

I have complex PTSD, agoraphobia with severe anxiety and lately im in a rut. My therapy has just began i had my first appointment last week so it is going to take time for me to bounce back. But as of right now, I cant go out, I cant get out of bed, I cant get washed or brush my teeth i just want to disappear. I dont want to see anyone but my fiancé & I am avoiding everyone as my panic has become uncontrollable. My mil just rang my fiancé saying she was going to call in and it was completely unexpected!!  (She never does this) so i told him to let her down nicely and say we would maybe call around to her and she started shouting saying "that is just strange behaviour!!!" and hung up. What can i do in this situation? Should i text her and let her know im not really doing well and need some respite???? 😞