I highly doubt legal action could do anything towards you. he's just an ass that's trying to scare you

Why did you accept that level of support from someone in your friend zone? Was it unintentional or were you simp-baiting?

Clearly you took advantage of him!

Here’s the way I see it: He brought it on himself by spending money on you without being in a romantic relationship. However, it was also on you for accepting expensive dinners, auto repairs and things of that nature knowing you didn’t reciprocate his romantic feelings. It sounded like you expected him to be at your beck and call while you explored other options. Which is kinda selfish. He hopefully learned his lesson to not invest in someone who isn’t romantically interested in them, and hopefully you learned your lesson not to take advantage of people.

Unless he can prove they weren't gifts and has proof you agreed to pay your share he doesn't have a leg to stand on.