Hacked.

Im a really secure person but today I was compromised. The full story starting from the beginning is that I used to play Roblox, but I gave it up to my little brother. He now plays on the account and I supervise his sessions because my account had a hefty item in it. Now on the 25th of March I come and log in and it’s gone, and I now have builders club which you need to buy to trade items. How the fuck did this happen? The hacker bought builders club on my account to trade my item, they also added someone to my account which I believe is just a proxy account. The money they used to buy the membership was probably from a stolen credit card on the deep web. I already messaged support. Do you guys know anything that I should be doing? My end goal is getting my item back, securing my account, and if I can, fuck over the hacker.