I had a placental abruption w/my first baby, at 29 weeks 5 days. Very similar to yours, except that b/c of prematurity I went straight to the hospital via ambulance.
Listen, your body and your intuition were telling you something was wrong, and YOU TRUSTED IT!!! It was not you at fault--it was your midwife's for not listening to you and trusting a mother's intuition. You trusted her to listen to you and to help take care of you and your baby, and she allowed her personal biases about laboring mothers or something get in her way of hearing what was laid on your heart! You did nothing wrong, except to place your trust in a professional who should have done better that night. I'm so glad your friends and family were there that night--there's a reason things work out the way that they do!
I knew all week long that something wasn't right and was headed south, but my midwife didn't believe me either, b/c nothing had been seen at any of my visits w/her or my doctors. My bp started to get a little wacky, started getting dizzy and seeing spots, my hands and face swelled off and on-all signs of preeclampsia.
As for my little 2 lbs 10 oz 29 weeker who inhaled my blood and stayed in the NICU for 38 days (one like where your ds may be transferred to), he will be 3 yrs old on Thursday and is thriving. He had issues due to prematurity that were a bit more long term, and lung damage that is both the prematurity and the blood in his lungs (respiratory distress at birth, resussitated, intubated, etc). He ended up w/asthma and RAD (reactive airway disease), but it's beginning to go away now, and he's not on any meds for it at all. He even caught a cold a few weeks ago and didn't need any asthma meds or treatments for it. He's smart and funny and does everything he should (and a lot he shouldn't!)
Hang in there--I'm not a professional in this field--just a mama w/a bit of similar experience and I want to give you some hope right now. They will take excellent care of your baby, but never be afraid to trust your intution and go at 'em Mama Bear style when necessary! It's okay to ask questions and be demanding about his care--just do your best to be open minded and respectful when discussing things w/his caregivers. Try to find one-two nurses and docs that you really mesh with and keep in close touch w/them. It helps.