If we were to engage in consensual sex at faster than the speed of light, would I go back in time, so that he would end up having sex with a 5 year old girl?

I did not force her, I just use my experience to persuade her to accept my love, we are consensual .

Love is two people of the everlasting, is not a person's wishful thinking.

And second, how can I square my interests with safe, sane, consensual play?

That's not to say that you deserve the mistreatment that makes you angry or hurt. It means that no adult in a consensual relationship is ever a completely innocent victim.