Is this Postpartum depression and what can i do about it?

I have a 2 year old son and just had a daughter 5 weeks ago. After I had my daughter. i was incredibly happy, so happy that i knew things could only go down hill after. I was right they did. I've been completely miserable, stressed, and moody. I hate my husband most of the time and just want to get away from my kids. I've had very suicidal thoughts and negative thoughts towards my baby. I never felt this after my son. I felt an instant connection when he was born and now with my daughter i dont really want anything to do with her. Its not just her either i want nothing to do with anyone around me. I just want to take off. Parents who walk out on there children have always disgusted me. I would never do it tho or hurt my kids and i know i love them but i've just been miserable lately. I've felt crappy for about a month now but now it seems even worse. I am crying a lot, and been acting selfish. I dont care to clean even tho im a stay at home mom. I dont even want to go shopping which i use to love doing. I hate felling like this. I dont know if im just having a crappy past few weeks or if this is something more if it is what do i do? I have my 6 week follow up in a few days and will ask my dr but can anyone else offer advice, or anyone know what im going through? I feel ashamed and like a bad parent. I have yet to even tell my husband about this all. And is it possible to have ppd with my 2nd child but not 1st?