helpppp

Okay so my SO is just as adventurous as I am and we both wanna try new things in bed each time. The last time we tried anal sex, although it did hurt (we used a lot of lube though), he gave a few pounds and I couldn't take it anymore so I told him to pull out. When he did, there were shit stains on his dick and I have never been so embarrassed. Any suggestions on what to do to not have that horror repeat itself? Beause he still really wants to have the full satisfaction of anal sex.