
Although it is under the circumstance you are going through right now, I welcome you here to the board. You are in the right place and I know you will find the support and some of the answers you are seeking. I know the pain, frustration and confusion that you are going through (first hand) - and a lot of members will be able to share their stories with you and you will know you are not alone.
It can't be easy to have had such a nice night and day, have everything seem to be going one way only to get home and have the whole world turned upside down. Is it normal? Sadly in a case with a pwPD... . yes it can fall within the range of what they are capable of doing. I can't speak for if they 'normally' come back or not (everyone is different) - but I would hope to focus you on some of the more immediate issues, such as the safety and welfare of your child.
If you haven't seen her in 9 weeks, I take it you haven't seen your child either? Do you now if they are alright? Did she just leave and take your child or does she have custody to be able to do this? I'm hoping you can be in a position to ensure the safety and wellness of both your child and yourself - and deal with the your s/o as a separate issue.
Do you not have anyway of contacting her?