am I wrong to want to cry.

So, I rescued a few baby robins in which I let go after they learned how to fly and search for food and all and still see them around well, a few months ago my brother found yet another baby bird the only problems is that it's wings were cut to be what looked like it was from a lawn mower so I fixed her up and just a few weeks ago she finally started eating on her own and finally drank from a bowl instead of a syringe. Well she started getting aggressive and I knew why I just had gotten so attached to her. Well I let her go to day and she was so happy. Got inside and literally just cried. Is that bad do I even have a reason to cry.