Well you dipped your toe in and no harm came of it so now you can say how things are:)
There is no need for any mask here, just say how you feel.
As someone who has an ongoing anxiety condition I can relate to both the mask -faking it -and the underlying thoughts of not feeling you can do things, or people will judge you and all the rest.
This is completly exhausting, and you are doing an impressive job in carrying on, going to work, and not staying in bed, not exercising and not using alcohol.
The idea that your circumstances, "cool job, boyfriend, nice house, fit etc..." has anything to do with it at all is simply wrong, they are irrelevant. I had similar, simply made me feel guilty and worse as a result.
That mask does, it is true, enable you to go though the day without awkward questions being asked and without people knowing what you are like inside. I found it was a sort of instinct to do this. Unfortunatly it has a major downside, you feel isolated from others because you are not realy interacting with them, and at the same time if you hide yourself you end up feeling what is inside you is somehow wrong and should be hidden. That feeling is far from the truth.
So firstly may I ask if you are under any form of medical support? I tried to improve but simply kept on getting worse until I had competent medical treatment. It can be had to go to a GP (booking an extended appointment) and setting it all out but can be well worth the embarrassment and even fear.
I now live a life wihtout a mask and am confident in my abilities, and happy being with others and working with them -a vast change. This was due to the medical team - it was also due to understanding family support
Apart from doctors and such do you have any personal support? anybody -family or friend -you can talk with honestly and just get a feeling of care and support? Trying to cope with all this on your own is extra hard.
I hope you come back and we can talk some more