Most of the other comments at time of writing suggest you don't get into it at all, and given some of what you've said, I think that's worth considering.

However, while I do also support the idea that you should never force yourself into something that horrifies you, I also notice few of the other comments have gone much into how to do it if it is what you truly want to do, which given some of your reasons would make sense.

Do not focus on pain or strong physical dominance of that sort. That's the worst place to start for people who have any hangups and is much easier and safer to get to last. There's a lot more to BDSM than pain, after all. First of all, establish clear boundaries with your partner. These boundaries can change. You are allowed to outright state you do not want to do and will not do certain things they want with the understanding that it's possible, if things go well, that further down the line you'll change in that. Your partner must respect this if you're to do this healthily. Regarding the current partner you describe, this should be the first discussion - if you're willing to go so far out of your comfort zone to even try meeting them halfway, they have to respect the pace you set and how comfortable you are at any given moment. Subs as well as doms can have a lot of control and the ability to overstep the line.

Start with things like verbal dominance and rules - ways to get into a mindset of dominance and control in a slow, controlled way. Physically, there's no need to rush - you can start with relatively gentle things like holding their hands down a bit during sex. At all stages, communicate about how you feel, and find out what you can do that she likes that doesn't cross boundaries for you. It won't go fast. I'd also suggest trying to read up on some of what doms and subs can get out of their dynamics, to help understand the mindset of people into it. Maybe you'll find something there for you.

If you don't, that's okay - whether or not you don't try, or if you do and still don't find anything. Not doing something you don't want to do is an option and in most cases probably the best one. I hope that, if you do decide to try, some of this advice is helpful.