getting along help

Ok so I'm not supposed to come around when he has the girls. couple weeks ago I stopped by his place to talk to him after he got off and before he usually picks up the girls. Well this day the ex dropped them off parked next to my car. got out of her car and started screaming at me calling me a stalker took my pic and a pic of my plate. and threatened to call the cops on me. words were said I pretty much called her a bad mother for staying all night at the bars and different guys houses while leaving the kids with her parents. long story short him and I are talking trying to sort things out and he said if we start trying to date again she's gonna make his life a living hell and threaten to take the kids and he doesn't want to loose them. so I need to win her over and get along with her. and i need to get along with his best friend. how do I go about that? I've been praying about it all and me and his bestie are finally talking and getting along. we're trying to plan a girls night but she's swamped till school starts. any help or advice on the ex? she doesn't know we're talking again. he said to wait a month to tell her and just not come around when he has the girls. . .