Son being bullied and miserable...Wwyd?

[Badvoc]

Sooooo....
I finally know why my ds2 is so distressed about pre school all of a sudden
He is being bullied
I just fucking knew it.
A child does not go from happily running in every morning to clinging and begging me not to leave him for no reason!
I had a word with pre school last week and they said no problems.
So I accepted this.
Then today I took him to a messy play session for kids and mums in the afternoon...oh my god
One child who hasn't been there too long (conincidentally after he started was when DS began to be upset) was simply vile to him and his mother just sat there.
I am so upset and angry and dh is away and I don't know what to do.
I can't go through this again. Ds1 was badly bullied from nursery right though to year 2 by the same child and school always played it down.
This child took every toy Ds2 had, snatched, pinched and crushed his hand.
ds2 shares well and gave the child the toys without complaint but it broke my heart.
The child ended the session by screaming and throwing a brush across the playground. His mother then stepped in. Oh, and she is a teacher apparently (this is relevant bear with me!)
After the session I spoke to the manager and said well, now we know what the problem is! She said this child had never behaved like that before and that his mother works full time so it was perhaps because she was there?
I am so angry with the pre school...there are only 8 kids to 2 key workers most mornings so there is no excuse for missing this.
Wwyd?

What does your son say happens at pre-school?
It takes a bit more to get boys to tell you sometimes.
Can you ask open/non-leading questions:
What do you like at pre-school/what don't you like/what makes you cross/who do you like to play with?
I understand why you are furious, I would be too. You have to feel satisfied that a pre-school will not put up with bullying, ime if they won't deal with it satisfactorily the only choice can be to move somewhere else.

Thank you so much for replying....I am sat here with dh on a business trip in the US and trying not to let the kids see me cry :(
I am angry, not just with pre school, but also with this mother who just sat there.
Not sure what to do.
Don't know whether to even tell dh as he is working and dint want to upset him, but I need advice.
Do I send him tomorrow? This child goes in a Friday.
Do I send a letter?
Apparently the nursery manager, his cm (who was also there) and his more say he never normally behaves like that? Implying it due to my son?
He just sat playing nicely!! And sharing, and laughing with the other children!l
I feel sick.

He doesn't say much...my elder boy was e same...a lot didn't come out til I took him out of the school, then we find out the severity of the bullying.
I realise my experience with ds1 is colouring my view somewhat but I am not sure I trust them anymore.
What can I do?

Aren't you jumping to conclusions somewhat?

In what sense?
My son was quite happy at pre school until approx 2 weeks ago.
Then he started crying at night, begging me not to leave him and being generally very distressed.
This boy started at pre school 2 weeks ago.
The behaviour I saw this afternoon was awful and all of it - all of it - aimed at my son.
What would you think in my place?