Advice

So my husband totally changed after having our son. Both his parents are complete narcissists and I’m thinking he is too. He does what he wants when he wants to and how he wants to. He spends money we don’t have and we are constantly in debt. He’s tanked my credit. He didn’t help whatsoever with my son for about the first year and now barely helps and spends most his time playing games on his phone instead of with our son. I’m debating leaving him but He’s an alcoholic and a type 1 diabetic and suffers from depression too so I don’t want him having overnight visits with our son because he’s always drinking and has frequent overnight low sugar issues where he has to have help or someone to call 911 for him because he becomes unaware of his sugar dropping and needs the help. He’s also increasingly becoming unaware of his sugar dropping during the day when he’s awake and on several occasions has driven with low sugar. I also found out why his ex left him which involved him killing her dog because she said she loved the dog more. He only told me this recently after 6 years of me asking why and telling me she just got back with an ex. So again I worry if I leave he may bring harm to my son or me or our cat. I want to keep my son safe no matter what and I don’t believe being with him is safe. I don’t want to get into court though and lose and risk not being there for my son while he’s staying with his dad. I feel like all the stuff I’ve said should allow me full custody but I also know the court systems aren’t exactly great and I couldn’t bare to sit there worrying about him with his dad. Help!?