How to tell parents/family I have been seeing someone who is older?

I am 20 and he is 31, we met online (on an app through chat). Not a LDR, he actually lives in my town. We have met up about 5-6 times now to hang out at his house, went out on a couple dinner/lunch dates... and just recently stayed over his house.

Keeping this a secret from my family is driving me insane. Usually my parents aren't very nosey, but ever since I broke up with my previous boyfriend they are always asking where I am going. I also have extended family visiting, who are also being quite nosey to what I'm doing and where I am going. (Poor timing)

I am suppose to be seeing him tomorrow, and I am honestly running out of excuses to where I am going. Should I tell them before I go over his house? I am not sure what to tell them...

Should I immediately mention his age, or wait it out until they are used to me dating someone new?

Should I just say "I am going on a date with a guy I met"? I'm just concerned about what follow up questions they will have and how I will handle them.

Recently when I have been going over his house he asks me, "Did you tell them where you actually went this time?" and when I say no he seems a little disappointed.