My MILs partner smacked our 3 year old

[BubblingRage]

Sorry for this being very long winded!
A bit of background first. MIL moved her new partner into her house after talking to each other for a month during the first lockdown. Everything was very quick and he seemingly arrived at her house with nothing. No furniture, towels, tv… literally just a handful of clothes. I always found him a bit “iffy” and refused to let my then 2 year old round to his nanny’s without me or my husband being there. (Once lockdown lifted obviously). Fast forward nearly 2 years and I’ve warmed to him, so I finally agree for my MIL to have our 3 and 1 year old overnight near Christmas so we could go out a celebrate my birthday. For a couple of weeks afterwards my 3 year old didn’t want “nanny” and (I shall refer to him as) “R” to come round our house. He also started not wanting to go round to nanny’s house either. This was very unusual as he usually dotes on his nan. Alarm bells starting ringing.
They came round to ours on Boxing Day as their surrogate Christmas Day. I noticed that R was often rolling his eyes and shaking his head at our DS. He wasn’t doing anything wrong, he was just an excited 3 year old at Christmas!
DS didn’t mention anything for a couple of weeks so I assumed he’d forgotten all about whatever was bugging him. Every so often he would drop into conversation or just randomly say that he doesn’t like “R”. I lightly questioned him about it but never really got a proper answer out of him. My DH asked MIL if anything had happened. She said R told DS off for throwing a dice. So we assumed that was what was wrong!
This morning DS randomly said again that he doesn’t like R. I sat him down and said that I will always help him. I always believe him and will never be angry or sad if he tells me what is bothering him and that I will always help him. But that I can’t help him if he doesn’t tell me what’s wrong. He then said that “R” smacked him round the head when he had a sleepover at nanny’s. Nanny had gone to get him a drink, DS was playing with a dice and R smacked him. He didn’t tell him off or shout, just smacked him.
I am beyond livid and although he’s only 3, I believe my son implicitly.
I don’t know what to do. We’re going to mention it to MIL and not let DS round to their house. But I feel like that’s not enough!
im just absolutely gutted for my son. And I’m so annoyed that I didn’t listen to my own instinct.
What would you do in this situation?!

He did it because he thought he could get away with it. The unfairness of being hit about the head as a three year old by some nasty man, poor little boy.

Agree, he is confident that he will be believed because he is a man and it will be easy to dismiss what a 3-year old child says!

I'm going to hazard a guess he's never, ever thought it acceptable to hit his girlfriends grandchild or it wouldn't have been hidden.

I am so sorry that you find yourselves in this situation. You have every right to be angry, and afraid too if I were you. Please do not allow this person anywhere near your children, there are no mitigating circumstances for striking a child, it is assault. It does appear that, perhaps due to lonliness, your mum has chosen poorly but you must discuss this with her openly, perhaps without that person present? She needs to know but may be completely unaware of this side of the person with whom she is living. Your son, small as he is, needs to know that mum, dad and grandma are there to protect him always.

Yes, I’ve read all op the OP’s posts on this thread. Just because the OP hasn’t stated some of these things, doesn’t mean she doesn’t know the answers to them - or if she doesn’t, that this may prompt her to try to find these things out.

It might well be that MIL is now regretting her hasty decision to have R move in but feels it’s difficult to extricate herself.
May be, OP, once you’ve ensured no more contact with R your DH could offer her support to ditch R. Just a thought.
As to the frequency of child abuse I remember my feelings back when I first had professional access to child abuse files, — it seemed that it was so frequent that more families than not were affected. Of course that is not true but it is more frequent than the rest of the population is aware of and, interestingly, in most areas there are interconnected families where it is the the norm. It is so sad and there are no easy answers. Social workers don’t have enough resources and are damned if they do and damned if they don’t. Good foster parents are worth their weight in gold. Inadequate ones just compound the problems.

Google isn't showing any statistics for those blinded by a flying dice...
He is just an abusive cunt op.

Contact the police now.