If he’s using cocaine, I’d only do supervised visitations. He could come over with you in the house or spend time with the kids with you present, like an hour, play with them and leave. Or it could be court appointed social worker in a neutral place.

I know people who are not bothered about cocaine use. Use themselves and have partners who use. But it’s illegal hard core drug so no it’s not ok. Doesn’t mean drug addicts shouldn’t see their kids when they are sober and test negative. Just never unsupervised until long time past and courts determine he’s clean for a long period of time

Do file for child support though. If he can afford expensive drugs, he can afford to support his children