Absolutely agree with what everyone else has said @Define_normal . Things are different now because you are a parent with a job of protecting and looking after your own children and their welfare. In order to do that, you must look after yourself and set an example of healthy boundaries and relationships to your children. Looking after yourself includes saying no to past toxic relationships and toxic people in general.
I understand that is hard, but you are worth it and deserve it. And so do your children, by setting that example they will see that it is a normal and healthy part of life to say no to toxic people for when they grow up (assuming they are minors, disregard if not)
CPS/DoCS may not be the best at all times, but ultimately it is their job to step in when children can't remain with their biological parent/s for whatever reason. Not your job. If it hasn't reached that point, it can be left with DHSS (dept of human and social services) for them to sort out.
(Jeesh that was hard for me given my experience, but it is just mine.... I do know foster children of more recent times who have great homes and who have even been successfully adopted so they don't have to age out like we all used to when I was in care)
Stay strong and stand your ground when necessary. It may seem ugly at first, especially if doing it is foreign, but it will be worth it in the long run. I had to do the same to a lot of people and services after I left foster care, and even more recently, and despite me having no family and next of kin because of it and no support either, I am a lot better off than I was, even though "better" was like a slap to the face of sudden realisation of how bad shit was and how negatively it impacted me.
Emergency, police & ambulance (24 Hrs)
Connect with a lifeline crisis supporter (24 Hrs)
Suicide callback service (24 Hrs)
Kids helpline (24 Hrs)
13 YARN