Your feelings are absolutely normal. Any one of us would likely feel exactly the same. (I know I would.)

I do want to reassure you that you ARE important still and always will be. No, you are not your T's child. Yes, your T's child will mean something to your T that is different than what you mean to him. But, your T's child will not replace you. The feelings your T has towards his child will not take away from his feelings towards you. In fact, I would guess that, ultimately, it will do the opposite. I know that having my child has softened me so much towards all people. It's brought about new understanding of how vulnerable we are as children and how horrible it is for someone to abuse that vulnerability. It has made me more furious at those who hurt children. It has made me more protective of those I care about.

I would strongly encourage you to talk about this with your T if you can. I know that it hurts in a very exquisitely tender spot. I believe that you and your T can get through this and even be better for it. HUGS.