I don't know a lot about BDSM? Are the messages purposely meant to demean you (as in role play)?
Regarding him not criticising you:
And, you'll notice, I haven't said what you are doing is bad. What said was there are some things I like that you currently don't do. And a couple of things you do that are a little frustrating as they prevent you from doing the things I like...
That's a criticism.
Are you seriously going to carry on seeing him after that message? 
If it's a purely Fwb/sexual r'ship, fair enough. But if it isn't, I'd be running for the hills.
And of course you're going to be nervous seeing him again, he's just critiqued your sexual performance: telling you all the bits you are doing wrong.
First, it'll be the blowjobs, then it'll be the way you fuck, then it'll be the way you look, then it'll be the weight..
Listen to your gut! If you thought what he was saying was justified, why would you be feeling nervous at the prospect of another sexual encounter?
I hope I'm wrong.