to think that this is just not right?

[Halbwahrheiten]

Going straight to the point: MIL has gone to france with her boyfriend/partner/live-in-lover/whateverheis. She has left her 21yr old SN, severely epileptic son in charge of the house, himself (bad enough), her two dogs and her 10yr old. And the 10yr old doesn't even know she's in france, she told him that she is going to london to visit her XH's parents.
She hasn't told her XH (the boys' father) that she is going either, so he wouldn't have "free access" to the kids.

Everyone is entitled to a holiday, child-free or not, but it's the 3rd time in the past 5 months that she has gone abroad and done this. The first time SIL took both boys and looked after them as well as her own 2 kids for the week, last time we did.
This time, nobody apart from the 21yo knew that she was going away, and we actually saw her on saturday, the day before she left.

I keep calling the 21yo a boy, because that's what he is. He can't cook, he can't judge situations and is mentally at about the same level as his younger brother. His epilepsy is medication-controlled but he still suffers from fits and severe migraines.

AIBU to think that it's just wrong MIL keeps doing this?

Yes, it's completely wrong and I'd be calling social services.

2 10-year olds are not able to fend for themselves.

It's wrong. Have you said this to her?

One for the Social Services, I think.

Are you in a position to take them in until she gets back? If so, I would do so and then read her the riot act when she gets home. Warn her that if she does it again you will call SS. Or alternatively call the exH, tell him what's happened and see if he can look after them?

She is massively out of order and needs a wake up call.

Have you taken the kids? You can't leave them there by themselves.

I would call their dad. He has a right to know how his children are being looked after and I would hand them over to him. Let her deal with the fallout when she gets home.

Yes. Awful.
I think I would report her. And I have never ever posted that before.
Poor boys

Either have the boys to stay or call their dad and deal with MIL upon her return Alternatively call SS and deal with the fall out this will cause.

What does your DH think?

I agree with above - ss need to be involved. Also why does she not want the. Father to have 'free access' surely he could look after them while she swans off around the continent? Is her reason for not using their father as childcare justified or malicious?

Definitely one for Social Services.

Your MiL is completely wrong, but unfortunately it seems to be you that now has to do something about it. Both your husband and the boys' father should be asked to intervene immediately.

I also think it would just be the decent thing to do to offer to have the boys to stay with you at least at night, in case they get scared. The dogs also need to be let out and and fed - by your husband, perhaps?

Someone must have an emergency contact number the MiL and she must be phoned and told to come back straight away and sort her arrangements out properly.

She may well need a break, but so do we all and lots of us don't get one; we actually take care of our children or make proper arrangements to have them taken care of.

I could understand her wanting to give the 21 year old more responsibility gradually, but this seems like a recipe for disaster.

her and XH split up for various reasons. but he was abusive and now only gets access to the kids once every two weeks for 24 hours by court order, which is a vast improvement from the restraining order she had out on him when they first split.
He has never been violent to the kids and they aren't even aware of those reasons.
we took them home with us on sunday when we popped over to show something to MIL and found she wasn't there, then SIL picked them up on monday and FIL is coming to stay with her to help her out.
This is totally going to blow up when she gets back.

DH is fed up with his mother and doesn't want much to do with her anymore now, but that's not helpful.

oh yeah SIL has the dogs, I can't cope with dogs, they scare me senseless.

Sorry X-post.

Well, I guess you have your answer here. Your MiL is out of order.

Someone will have to calmly tell her to (a) come home and take responsibility; and (b) never do this again.