My question involves a child custody case from the State of: NJ

I am trying to prepare to ask the court for supervised visitation of my children. My ex has petitioned the court for parenting time. Since I separated from my ex approx 2 1/2 years ago, he has only seen them 5-10 times at family functions or when I initiated a visit by calling and arranging it. My ex has a history of drug use and mental instability. He is very inconsistent and I have a difficult time reaching him to discuss the children. I have not let my children go to his current home because I feel it is unsafe/unstable (fights, arrests for drugs, child protective services). Over the past 2 1/2 years, I have offered for my ex to visit at my home or at a member of his family's (sister, mother) homes but he has refused. I am concerned about their safety if they go to his home. My ex also apparently has some health issues and has reportedly fainted/blacked out. I'm worried that this could happen in front of them.

I am not opposed to him meeting and visiting his children, I just want it in a safe environment and on a consistent basis, not just on holidays which is usually when he will call them. Since my ex hasn't seen my children regularly and he has history of drug use and health issues, what are my chances of being granted supervised visitation? Thanks for any advice!