Having a hard time sending my baby with my ex and new girlfriend? Help!!

Soo my ex husband and I got a divorce not too long ago, I know he has the right as a father to see his child (2 year old son) I promise I do not want to be or sound like those girls who use their children to hurt the ex in any way. I respect him as a person. And even though we still bump heads, I still love the man but I am trying to learn to let go -of everything and adjust to my new life. The hardest part is letting my child stay with him on the weekends. 😭The reason is because he is my only child and we had a hard time conceiving him. He is my everything and I'm so0o0o over protective of him. Every time he's over at his dads I call/text a lot to make sure he's okay. I know his girlfriend is starting to get annoyed by me. Even though I love my ex still, my intentions is not to break them up or anything I just want to see how my child is doing. Also, I'm afraid of the girl being around my son. I mean you hear all these stories about step parents abusing the step kids and I'm freaking out. Since the first time I met her she rolls her eyes at me and seems to be one of them gold diggers. She is a cousin of a friend of a friend and I heard she has a crazy party life style. Which surprises me because my ex always talked down on women like that and is a business man. Anyway, This is all new to me, Is this normal? How do you ladies cope with this?