It sounds like you are saying that you take risks because if anything goes wrong it's okay. The loss would be at your expense and to your harm, and you don't matter.
The same when you say "it's just sex". The implication is that real commitment and genuine sexual fulfillment are beyond your reach, so at least let's have a good fuck. But it isn't really good is it, when "during the thing I was afraid he would drive off and leave me there or cut me or something"?
I don't mean to sound harsh. But I hope you can see this is all classic "acting out" of your fears and anxieties about yourself arising from abuse. It's important to know this, because then you can make an informed decision about what to do next.
That is, you aren't stuck with this. You can do a lot better and live your life in a lot more joy and satisfaction - including sexually - if you wish to do so. But there's the grab: "IF you wish to do so". When we are spinning our wheels in acting out - whether its sex, porn, alcohol, drugs or whatever - the only person who can break us out is ourselves. We have to make our own decisions and then follow through on them.
When I was a student and more or less lost in alcohol and drugs, a teacher of mine told me I had to decide: do I want to live my life or lose it? Back then I thought he meant "lose it" in the literal sense, drinking myself to death or ODing. But he meant more, I think. A life thrown away on ephemeral thrills is also a life lost.
Nobody living can ever stop me
As I go walking my freedom highway.
Nobody living can make me turn back:
This land was made for you and me. (Woody Guthrie)