I have a father that can’t be trusted with my dc, I know how hard it is to walk away from the dream of a loving extended family and support, but you absolutely must op.
The children’s relationship with you is paramount, absolutely paramount. Their relationship with grandparents is optional and secondary.
Given the choice, do you think they would want their stability and safety compromised for a few fleeting visits with either of your parents?
Of course not.
You are still in denial about what has happened to you (SS would never make stipulations like that without a very good reason) and because you can’t face up to the truth - understandably - you are endangering or could endanger your children, you are compromising your position as their main care provider and potentially putting them at risk again with your father.
Your mother is still with your abuser, still enabling him which is why she can never ever be trusted.SHE will always put him first over and above you, over and above your children’s safety and well being. That will never change ir she would have left him by now.
You can continue to see her if you want to, but keep your children away please, for their own good. It’s better to have no gps at all than ones that endanger them in any way.
And no, he will never change. Ever.
No your mother will never change either
Your best bet is to find safer forms of support from TODAY and show SS your progress and safe decision making. Vow not to let either parent near them again.