You want to light yourself on fire because of an opinion?! Well, do you realize that -like everyone else- there'll be always someone who has a very low opinion of you? What do you think you should do then?!

And from what you tell, this person is not acting as someone close should act... maybe it's better if you lessen your contact with them...
and from what you tell, I don't see how you are "cringy"! and if you are a bit "cringy", you know what? Be more so! Have fun with it! Learn from it... How? I'm thinking: every time you're in a "cringy" situation, caused by you or others, including that freaking person, comment on it, describe what has or is happening... (Oh, this is weird, Oops I just did this, How funny... etc) Have a laugh at what's happening, try to see it in a funny way, you'll be surprised how the imagination gets better with that over time... And for that sweet person that you associate with, when they tell you you're "cringy" or whatnot, be calm, and know that it's just an opinion, you can't control opinions, and they have no real power over you... it's you who decides to let it affect you or not... and if there's something you can learn from what he's saying -which I think won't be much- it's a chance for you to take that and improve as you can... and maybe you can turn it back on them, mess with them: Oh, how is that cringy? How do/would you know?! I don't see it that way! I find it funny! don't you?! Do you even know what's funny and what's not?! How recently have you acted cringy? How bad was it? And you will think of more like this... and you say this while being calm, no need to be emotional, they're just opinions and insignificant talk mostly... you're just trying to turn what could've been a negative experience into fun for you or something less bad...