Hello, Beverlee. Just wondered if you found any helpful ways to deal with this? Kind of have similar situation at my work (there always seems to one!)
I had some sleepless nights trying to find some resolution to dealing with this. While it's still a work in progress, I hope you won't mind my sharing a few things I'm doing differently.

When all else fails, I just commit to being polite. When I'm irritated by the coworkers behaviour, I try to default to basic politeness

Withdrawing from situation- when they start on their stories, competitive behaviour, etc I excuse myself (have to run to restroom/that's my phone!/have a deadline/etc) to physically remove myself

Allowing them to dig their own grave - I've seen that by talking too much, verbally swaggering and bragging, telling tales, people eventually torpedo their own battleship. It becomes evident to everyone else that this person is not someone to take seriously or to trust

I try to tell myself, that if I can find a way to deal with this it will increase my value as an employee. You have my sympathy!

Take care - hope you will share what has been working for you...