text: my sister in-law and i got drunk last night and we made a huge mistake by going to bed.  what do i do now?   oh man you just opened up a can of worms. your best bet is to forget about it but that will undoubtedly anger her. just forget it ever occurred and absorb whatever wrath she has for you.  ps, remember, you were drinking, so you have plausible deniability, i.e. "i do not know what you are talking about". this should be your standard answer to any referance to what happened.