Unlike most other people i do not consider reality and fantasy being something diffrent, what really matters i how much you are willing to pay for your desire being realized.
Which is actually the universal criteria for mental illness in all contexts. (except when your mental disorder suits society)

letting a woman piss on your face is pretty cheap desire if you manage to find a woman willing to do it.
but being punched or whipped while may be pretty sexy will cost you few days or even weeks of pain and annoyance with some level of disability.
So are you willing to pay that price for few minutes of pleasure?
Do you even like pain and suffering itself or you are just into action and looks?

If yes, then what is the problem? Just do it pay the price and also post some pictures for us to fap on them. You do not need to stop yourself if you are absolutely sure that it is worth doing. maybe you will even die but who cares that is the price you are willing to pay.

If not, well then too bad it will remain just in your dreams on how great it woud be if someone choked you to death and maybe look for pictures of people who paid the price and enjoy their experience trough the empathy.
also you can try to draw yourself in those situations write stories or ask someone to do it for you. I think it is not that much diffrent from really experiencing it.

Finally what you imagine can be very diffrent from real thing so it is not necessary that if your dream came true you woud get any pleasure from that at all, most likely it will end with disappointment. Extreme level of stress and doubt will also make everything worse.