Commiserations, TFL. But well done. You did the gig, you've analysed the situation and (most importantly) you had some positive feedback from a more experienced stand-up. The people in the audience will not remember you tomorrow. That audience is gone, they're the past, forget about them. Your next gig is a new chapter. Get back out there, try to perform your set better from a technical standpoint. If some laughs come your way, well, that's a bonus.
There's a massive difference between making people laugh on a one-to-one basis compared with doing stand-up to an audience. It's a painful lesson to learn, but if you keep at it you will get there. There are stand-ups that successfully work the circuit with only very average material. Extremely thick skins, technical polish and determination has got them there.
It's always shit the night you've died on your arse, but you'll survive. Most people would not even have the guts to stand up in front of an audience and tell a single old knock-knock joke, let alone their own material. Remember that and best of luck with the next gig.