Basically your parents are the alcohol addicts and you’re saying they get violent when drunk…?
Must be really hard as your their only child and I’m guessing all the burden is on you .. you must be worried for them all the time .
1st of all I personally think your parents should separate if they Crnt control their addiction because them living together isn’t helping them.
Could you not keep your mother to stay nights with you so you can keep them apart . The alcohol addiction might not go that way but it may decrease the limit of Alcohol they consume and the cut down the risks.
Sorry to say but they might just end up killing one another.
Have you tried to get professional help for them both?