Just picked up this thread and I thought I'd add my thoughts in case they help at all...
I had PND after ds1 and felt quite trapped in an unhappy marriage when I discovered dh had been having an affair. I was contemplating doing the same, just to get back at him, to make me feel special, to hurt him, to get noticed, oh a whole range of reasons... but just in many ways to break the monotony.
Not sure how, but these thoughts came out in a conversation with my GP (very caring lady)... she had a few suggestions to get some control over my life FOR ME and one of these was to go to the local beautician for a bit of pampering...
Just for me... not him, not the baby or anyone else...
It was a fabulous feeling (although I felt guilty, I wasn't as riddled with guilt as I'd have been if I'd started an affair!) to go long and book some treatments... I had a full aromatherapy (uplifting) massage with relaxing music and special treatment that made me feel so wonderful for quite some time afterwards.
Now I don't do that anymore, but I do get my nails done eery three weeks (again "just for me") and just to look at sexy nails on me makes me feel like another woman and special...
Just thought I'd share... find something specific that appeals to you maybe...
"Because you're worth it "