Dealing with PP anxiety/depression/psychosis & so embarrassed

I need to talk to some other mommies! My baby is 11 weeks old and I love him so much. After he was born I was soo relieved because we bonded so well and I was just glowing. Motherhood was a dream & things were wonderful! But eventually I became very paranoid all the time. I became convinced someone was in our home or that everyone was out to steal my baby. I constantly feel like I'm not a good enough mom. I can't sleep even when I'm exhausted, I just lay awake. I lost all interest in my amazing husband. He's been nothing but good to me yet I am repulsed by him. We have no sex life and I often get annoyed when he comes home from work. I feel so bad but I cant help it. The littlest things irritate me sooo much and last week I even got so mad at him I was ready for a divorce. I'm a SAHM & im so lonely. I feel so useless staying home all day while he works. I can't bare to leave my baby with anyone else and I want to be home with him but feel like I have no life now. Now the newest thing I'm dealing with is what's really scaring me. I have these awful nightmares of ghosts and demons. I wake up in the middle of the night convinced there is some kind of evil spirit in our room trying to get to my baby. I get no sleep because of it. I often just sit there and stare at my sleeping baby because I'm too scared to go to sleep. Today, I was so scared to be home alone I packed up baby and me and just drove around aimlessly. It's too cold to go for walks or anything, and I don't have any friends. I know I'm dealing with some kind of PPD and should get help but the problem is im SOO embarrassed. I can't even work up the courage to tell my own husband! I don't know why. I know ppd is common and not something to be ashamed of, yet I feel like such a failure.