Self-employed American with EU partner--tax and visa questions

Hello!

I deleted most of my post b/c there weren't any replies. Maybe someone will chime in now. :)

I'm American, living in the States. My live-in EU boyfriend is considering a two to three-year job in Germany.

How high do taxes on self-employed really get? I mean taxes plus social stuff? I've heard some very high estimates because of the obligatory health insurance. Is there anyone with experience who can share their experiences? Are there ways to reduce this through funding retirement (I have nothing except some meager social security at the moment)?

I know I will need to talk to a specialist, but I'd like to have an idea of what I'm dealing with.

Thanks.
xoxo

I updated my post, deleted a bunch of info. Maybe someone can help now?