Anxiety/PTSD and full-time work

I work full-time in an office through diagnosed acute anxiety, depression and PTSD, being treated by private and expensive psychotherapy and not medication.

I have been advised to apply for PIP as while I am capable of masking at work, I crash every evening and spend most of my free time unable to make plans, socialise, leave bed, because of my symptoms.

I am high functioning in order to keep my job but the consequence is utter collapse the moment my job ends and a personal life which is unfulfilling

I am told PIP recognises the concept of masking and that I would be eligible. Do you think this is true?