[USA] thoughts on my case?

Okay I have a four year old with my ex. He’s taking me to court to try to get 50/50 custody but I’m fighting it and am wondering people’s thoughts. My argument is based on a DUI he got two years ago (child was not in car). He moved out two years ago as well. When we were living together he drank all the time and alcoholism runs in his family. He claims to be sober now that he has been living with his new gf for the past 8 months but I feel like the alcoholism runs deep and he could be lying. He just got his interlock out so I’m worried. The DUI is the only legal thing that has ever been reported but he drank every night when we lived together! Would come home from work and drink, go to friend’s houses and drink. Apparently he’s been in therapy for awhile and stopped drinking a year ago but he could decide to go back to old ways any time.

We have no custody order. I allow him to have our child two nights/three days a week. He does have his own room and everything he needs at my ex’s house.

Another thing I want to use against him is he enrolled our child in preschool on his dad days and didn’t tell me until a week after school started, claiming it was “a trial week”. I don’t pay for any of the school because he never consulted me and I don’t agree with it. He says it doesn’t matter because those were his designated days and he listed me on the paperwork as mom but wtf he should have TOLD me before enrolling my child in school.

My son is also a mama’s boy. He cries whenever he has to go to dad’s and I don’t want to make him go there more than he has to because he’s attached to me! I filed against his 50/50 proposal for dad to see my child ever other weekend (+ Wednesday dinners).

Do I have a case here? Just want some feedback from Reddit community