So me and my sons dad have been together since 2012

He has had a new girlfriend since I was 5 weeks pregnant. I try to keep him involved I invite him to doctor appointments, ultrasounds the baby shower everything... but he always has a excuse not to come. He tells me I make his new relationship very hard becuase I wont allow her to be at appointments, ultrasounds, baby shower or the hospital when I give birth but I feel like its not her place. But now im bitter and I feel like why should I waste my time and effort when I already know the outcome and its getting to the point I want to cut him out because of how he acts I just want advice from other moms am I being to emotional and over reacting or is it normal to feel like hes trying to replace me with her when its MY SON