Worried our lives are ruined

Sorry for the dramatic title. I have a toddler who will be just shy of 2.5 when my twins arrive. I love her beyond measure, and sometimes I feel so bad that I’m having twins and that her life as she knows it is going to forever change. Sometimes I already feel like I miss her, it’s just this crazy feeling of guilt and that I just want to hold on to what we have now forever.

Did anyone feel this way while pregnant with the twins? Was everything OK in the end?