How to help someone through ppd

Tammy

First time posting but a little back story my best friend just had her first baby and a month before she delivered she and her husband had to pick up and move across country for his job. She had her beautiful baby girl on January 4th. Baby is doing great and dad is adjusting beautifully. But my best friend is having severe anxiety, saying she feels like she isn’t a good mom, feels like she is abandoning her lil girl when she puts her in her pack n play, can’t sleep because she’s afraid she will stop breathing in the night, has a hard time functioning normally, keeps saying nothing good ever lasts in my life so I’m just afraid that something bad is going to happen. She struggled with anxiety and depression before pregnancy. Her husband said it got so bad that he is now up with the baby through the night and he is so lost. They have no family or anything anywhere near them. I don’t know what to tell him I don’t know what to tell her and I’m on the other side of the country and I can’t get out there for a few months. Any advice that I can pass along?