I am so sorry this is all happening to you which is what should be a time of joy as you enjoy your son. It is so hard to have to go through this whole role upheaval especially when you had difficulties before you left.
I am not sure who at work, but I think you need to speak to someone, be it your manager, even though they are new, they still have a role to take care of you and essentially to get the best from you as an employee and this is not going to happen while you are feeling so hurt and so confused and uncertain.
The company should have addressed all these things with you when you started and outlined to you that the role you are doing has changed and that it is not a reflection on you and these are the reasons we have done this...then go about a change management scenario with you so you do feel valued and you do have peace of mind knowing what to expect and that you are a hard worker and they do value you. I am so sorry this has not happened.
I think so clarity here is needed for you so you can understand what the role now looks like, what is expected from you and why this things have occurred.
I am not sure if you want to talk about the PTSD, this too is alot to manage as well with everything that is going on.
You are so very right about your son in care though, they do manage and they actually do go on to have some resilience at a very young age, which is great. He will be cared for and entertained and then look forward to seeing his mum when the end of the day comes.
Hugs to you Kbo, this is really hard to have happen.