The one thing in this world you can not do enough of is covering your own behind. No one else will do it for you.
So, you’ve met some chick, and all of a sudden, sex happens. We’ve all been there. The problem, in this case, is that there has been no “memorandum of understanding” documented beforehand. This poses a problem in the #metoo era, given that you are now in a legal position which gives her the upper-hand.
Your duty, at this point, is to get her to say she had no complaints, in writing, and back this up to the cloud. Email is better than text message, but text message is better than nothing.
It should not escape anyone that currently, numerous wimminz are retroactively accusing men of harassment, rape, and lewd conduct, often years after the fact, with zero evidence, and that the male victims of these unprovable accusations are being socially and financially punished, regardless of the facts. If you are a man in North America, you need to take this seriously.