If you think that hooking up again would only bring more guilt, it's not going to be worth it. For your own sake you shouldn't have sex if it's likely to emotionally hurt you. (There's nothing to feel guilty about though, hooking up was completely your decision to make and lying to your family probably feels pretty bad but it's something that we all do and didn't hurt them.) Your comfort and mental health are more important than not offending anyone, you are perfectly entitled to say "that was great but my headspace is such that I'd just like it to be a one-off, thanks".