He is 6 months into recovery after many years of addiction which started at a young age.
I am guessing you did drugs with him but he was lying about how much & often he was doing drugs.
You have good reason to make the below statements:
" I am so scared to be vulnerable to him and get hurt again
I would essentially be opening myself up to future pain and possible relapse which scares me"
I cant predict how this turns out if you get back together but it honestly doesn't sound good. No matter which way it goes your in for a very rough ride.
Don't give him access to your finances. If he relapses, it will be off to the coke dealer then in the car & off to the casino or insert whatever gambling. Just having a couple drinks could trigger off all this behavior. Coked up gamblers can go through a ton of money & not even blink an eye.
I hope you also understand that coke, alcohol, & gambling addicts are not the faithful type. Its just the nature of the beast so to speak.
I hope you do a lot of reading & research concerning addition so you can make informed decisions. You should be extremely nervous & cautious.