Ex Mil Drove Away With My Toddler- Help!

Location: Rhode Island

I recently divorced my emotionally and verbally abusive ex husband. We have joint legal custody but primarily placement is with me and he only has our 3 year old son 48 hours a week.

In our agreement we have first right to refusal if either parent can’t be with him for 4 hours during our scheduled time.

In September, he called me the night before his scheduled pick up time saying he got forced OT (he is a police officer), but his mom offered to pick him up from me. I was trying to be nice, though I could have said no, I agreed for pick up time at my house (where I’m currently living with my parents) at 4:30pm. This would be the first time I was seeing her since before our separation and divorce.

Long story short, she showed up at 3:20, was very unhappy my child did not want to go with her, so she criticized my parenting, mocked me to my face, then sped away as I was opening his car door to take him out.

I stayed calm during our interaction and briefly explained my parenting style is talking to my child about his emotions and since she’s never picked him up from me before, this was new for him. I also asked her not to speak to me that way in front of my son and mentioned our first right to refusal agreement.

When I said “I don’t appreciate you speaking to me this way in front of my son, and I don’t have to let him leave with you right now,” she said “you can’t take him,” so I said “yes, in our agreement I have first right and I’m going to take him out of your car now” and reached for the handle, she said “no you won’t” and sped away in reverse.. I had to jump back so to not get hit…. All while my toddler was screaming and crying for me in the backseat.

After about 5-10 minutes (and an anxiety attack later) she showed back up, my toddler ran down the driveway towards me.

Since then, my son has not slept through the night with me, screaming and crying for me nonstop asking to sleep on me. He tells me he’s scared and needs me and he’s scared grandma is going to take him from me. I also noticed significant regression when he spends time with her, speaking to me in grunts and emotionally dysregulated for a day or two before returning to his normal happy self.

My ex-husband is very angry at me for this interaction, among other things, so I know he will not understand where my son is coming from.

I have so much anxiety about her doing another pick up from me, and I’m waiting to hear back from my lawyer about my options to permanently prevent her from picking him up from me in the future, but while I am waiting, does anyone have any advice?

What are my options? I know I can’t prevent him from seeing his grandma on his dad’s parenting time, but can I do anything to prevent her from getting him from me? If I file a police report, will she be notified? (I’m scared to do this because he is police and I know how it could get spun to be against me since they have each other’s backs… most of the time). Can I even do anything since I originally consented to her picking him up and then withdrew consent?

I want to protect my kid because I know I’m his safe place emotionally, mentally, physically, and I need to let him formulate his own decisions about his dad and that side of the family. But while he is three years old, how can I ensure my safety and his from this ever occurring again?

I apologize for the long post, this is my first time writing in, but I need some help to ease my anxiety while I wait for my lawyers response on this long weekend.

TL;DR: Ex MIL drove away with my toddler after I withdrew consent, what can I do to prevent her from picking him up from me in the future?