Co parenting in recovery

My ex walked out on us 4 months ago just as he got out of rehab and is seeing someone new now. I am just wondering if anyone has any advice on Co parenting with someone who tells you they are still in recovery attending meetings etc whilst navigating your own heartbreak? Similarly, I’m lost at how I go about protecting my child. She’s only 5, doesn’t know anything and spends 2 nights with him whilst he’s at his mum’s. Do I just have to trust he’s sober and that’s it?