K, so let's establish something first.
Arguing with an active alcoholic about money is as useless as untangling a ball of yarn your cat (or toddler) has gotten into. It's POINTLESS. It's easier to snip away at the tangle or throw away the ball and start with a new one.
Your partner is a mooch and a liar, like mine was. There was ALWAYs some valid excuse why he needed x,y,z, and about why he couldn't repay me, or about how he HAD repaid me but I'd forgotten like the b*tch that I was, etc etc. You know this drill; it's maddening. Considering the man is abusive, there is even less point in arguing. Arguing might get you beat up. Again.
Now, your lease has been changed so that on April 1st, you're the only leasee. How are you planning on getting your partner out of your house then? I may be mistaken, but the way you portray him, he is a bloated tick feeding off you any way he can. He's not going to let go of his favourite enabler without a fight.
I wonder if you shouldn't be discussing the situation with your landlord. Generally, you need to give a person warning before they relocate, though I'm not sure about the legal delay required by your city/state. Again, talk with the landlord...and perhaps make a non-emergency call to your local police. Ask them hypothetical questions...as in "I want to kick out my mooching partner. His name won't be on the lease as of April 1st. How do I get him to leave?". If you can't get answers from them, then call the National Domestic Abuse Hotline and see if they can refer you to an organism in your area.
Other SR members have asked / forced their A's to leave. Perhaps it would be wise to post a thread about the topic to get some answers from them.
I don't mean to scare you, but I forsee that just telling your A that he needs to leave on April 1st may result in some drama, and as it has happened in your case, violence. I think you may have to devise a strategy, and FAST, as it's already March 25th.