I'm not comfortable with his other baby mother

We got into an argument and instead of him driving my car he asks his baby mother to take him to the Chinese restaurant to pick up his food! Any other time he would drive my car but he got mad and said he will walk but his baby mother came to drop off their son and that's when he asked her to take him! I was looking out the window thinking he was still going to walk because he didn't ask for my car keys but instead I saw him getting in her car! I hauled ass downstairs with no coat or shoes on and pulled his dumb ass out of the car and told him he was going no damn where with her! Needless to say he went to bed hungry! That was so disrespectful because early in our relationship they use to flirt and shit and we have underlying issues so I don't care for that bitch!