My puppy passed away

This morning, my 12 week old Australia shepherd puppy died. I've only had her for two weeks and I feel like it's my fault. She was sleeping on the bed before she heard sound, got up, wobbled around, and fell off. She squealed and I immediately jumped up but it seemed it was already over. She was laying on the ground and not breathing. I tried giving her CPR but it didn't seem to help. She was gone. I held her body in my arms for hours hoping something would happen, even though deep down I knew it wouldn't. I feel destroyed. When I first got her she was such a shy dog. You had to carry her everywhere she went because if you set her down she'd just freeze there and lay down. She was terrified of my other dog, a 100 lbs sheepadoodle at first, always hiding under places he couldn't get to whenever he came around. It was the only time she would move on her own. Then some days went by and she started exploring. She would walk everywhere non stop back and forth smelling everything. She eventually got comfortable and tried playing with the other dog. Granted, whenever he'd get excited and try to play aswell, she'd start screaming and run and hide behind me. Yesterday, she played fetch with a ball for the first time. Today, she's dead.

R.I.P. Dakota, I'm so sorry. I wish someone else got you instead of me.