I am at the end of my menses having the brown discharge. Should I hold off on having sex tonight?

Sex at end of period. Sorry for the delay - there really isn't a medical reason not to - the discharge is simply the end of the menstrual flow. It might be a little messy but is harmless. There might be certain activities you might want to avoid after penetrative intercourse (hopefully you can figure that out) but that discharge is harmless.