AITA Caught husband peeing into cup

So I found (didn’t know he was doing this and walked in on him) my husband peeing into a cup. It’s an old ricotta cheese container actually. He looked like a deer in the headlights. He then dumped the cup of pee into the freaking sink. Rinsed and put cup into the cabinet. I’m standing there totally disgusted. This is my sink. (It’s an old house single sink – he usually during the day uses only the other bathroom down the hall). I brush my teeth here. I place my hairdryer and straightener in this sink while using. I lay my clothes over it when getting dressed. Oh my god he puts pee in there. He dumps it. Sloshed it with water once. Dumps that then he’s done. Says it’s no big deal and has done this for awhile now but I’m truly disturbed by this. Tried talking as I know standing for guys especially as they age is easier but dang stand at the toilet. He says he likes doing this better so he doesn’t really have to aim. I then said pour the pee into hmmmmm I don’t know maybe the toilet! Then use the shower to fill and rinse. Don’t use the sink! He completely dismissed my feelings. Said I’m overreacting. Help me understand. Is my telling him I am disgusted make me the asshole?