he more or less stuck to the safeword thing
I'm assuming you had agreed to the content prior to the booking, and you were happy to be cut and bruised, and you'd charged accordingly. (Cos let's face it, you're not gonna be able to work for a couple of days after, unless you work 'pimp-beaten crack whore' as a USP) All your tears and crying were fake, in order to enhance his experience with you.
If so, your only issue is that he didn't 100% stick to the safe word. If they don't stick to it, you need to kick 'em in the bollocks, knickers on, and off you go. The safe word is the unbreakable law.
If you HADN'T agreed to everything prior to the booking, and you didn't want to get bruised and marked, and your tears and crying were real, well, without wishing to sound melodramatic, I'd argue that it wasn't BDSM, it was assault.
As the prostitute, you are ALWAYS the one in control. If they are paying you to sub, they are paying you to pretend you don't have control, but you are still the one in charge.
My understanding of the BDSM lifestyle (ie the non-prossified version) is that it is always consensual - hence the cast iron law of the safe word.
As a disclaimer though - I've never done a BDSM job. This is just my natural reaction to what you've said. I'm interested to hear what the others have to say!