Just don't cheat on your hot girlfriend who loves you, is good to you, fucks you on the regular, and doesn't go behind your back to fuck other guys or even worse pays other guys to fuck her.
Something else is wrong dude. Talk to her about it (leaving out that you went to a provider of course)
Mongering is a pretty hard road, even for us guys who just do it for the sex. It can be pretty horrible if you are doing it for reasons other than just sex because it just makes you feel good without actually fixing what is wrong so pretty soon it becomes an addiction.
I know that you want to believe that you just want to do this for the sex, but the fact is that if you have a hot girlfriend who fucks you well and regularly, then sex is definitely not the only reason why you are willing to risk all that and spend money just to feel good for a half hour or two.
No judgment, just logic. If you are already getting good regular sex then you can't be doing this just for the sex!
Something else must be missing from your life, relationship, whatever. It probably isn't even something that big.
Talk to the woman you love about it before spending money on a woman who doesn't even know your name.
Good luck man, I know you didn't want to hear this (or maybe you secretly did) but you've got too many good things to lose and sex is definitely not your only reason for wanting this lifestyle and it definitely is a life style!