Sibling Sex Guilt

There were several incidents of sex play with my younger sister when we were kids.
I got her to show me her vagina when she had just turned nine and in exchange I let her watch me, in my early teens, just jerk off to it as she watched.
It could only happen when our parents weren't in the house, which was not often at all but when we were alone I'd get her to do it as we looked at online porn in my room. I know that by the third time we did it she asked me to lick her like she saw on one of the vids so that sort of became part of it as well. We did it like six or seven time over like almost two years because of the privacy needed. Then she just refused to keep doing it and fearing she'd tell, I backed off.