Adding another kiddo

I feel almost sad admitting this...but for six years (and a six and a half month pregnancy added) it has been me and my son Kahle (pronounced Kale). He has been my light and inspiration to be a good mother, a hard worker..kind and a good teacher..a fighter and protector......and today I found out I am (hopfully if my bean sticks this time!!) going to be adding another member to my loving family. I am with a wonderful man who took my son on as his own, and has been a stable partner in his patience and giving soul. We wanted a baby...we wanted a brother or sister for our son. But as I sit here thinking about what this means for everyone, I can't help but feel a sense of the bittersweet its providing. My little man who fought so hard to come into this world...won't be my little baby anymore. His sweet cheeks won't be the only child's I kiss at bedtime, and my time will now be shared with another. Is this normal to feel? I know that the love I will have for this little being im growing will be just as strong as my love for Kahle...I just know it's going to be different. Have any of you other moms out there had to battle these feelings? The almost painful realization that you have to let go of one to hold another? Does this make me awful to feel this way in a moment when I should feel over excited and happy that we are finally expanding our loving home? I love that little boy with everything....