comparison

[pellaz]

... is there a risk of STD transmission when I receive a facial? ...

Generally i would put it at low risk. With all thats been said on HIV and various STD transmission i am thinking along the lines you need to visit a local free health clinic for your self, quickly. Get tested and ask lots of questions. When was your partner tested? After you have been tested you need to have a talk with him about this. If he is not totally out with you bail.

Is it OK to enjoy sexual humiliation along these lines? .. just kind of fell into this.

Enjoy it while it lasts, if not forever. Most likely you will want to move on tho. Have an exit plan. Set your limits.