Playing us all off, trust gone and fed up

[NorthernNanny5]

Where to start , oldest DSS is 16 and lives with us full time. He spends random nights at his DMs.
He plays us all off against each other terribly (I know a lot of kids do) but things have gotten rely bad with it. To the point I feel distrusting of him in our home, he shit stirs between houses to his own advantage, he has told me on more than one occasion he looks in his DMs phone at her messages etc so now I feel I can't even leave my phone unattended in the house. He tell lies between houses a lot which causes no end of shit.
He also cherry picks when he wants to go to his DMs usually when he has been grounded so he can sneak out etc and gives us little or no notice of these plans (very annoying when I've cooked him a dinner) despite us asking him to give us a little notice.
On this subject I have now told DH he has got to organise with ex and DSS set nights as im fed up of not knowing what's going on in my own home from one day to the next and seeming its often me doing the primary care as he works away I feel my opinion should count.
I know teenagers will be etc but surely I shouldn't be living in my own home feeling like there is a spy amongst us!
Does anyone have any advice with squashing this playing off?

[Kaluki]

Children can only play their parents off against each other if the parents don't communicate themselves.
Easier said than done but you, your DH and his ex should all be a united front. If he's grounded at yours, he is grounded at hers too. I would tel her he snoops at her phone and make sure you put a lock on yours.
He will only get away with this as long as he is allowed to.

[NorthernNanny5]

Agree Kaluki and DH has basically told him, my house my rules, don't like it go back to your mums. DH spoke to ex about having set nights and she point blank refused yet said it was totally unreasonable to expect a days notice when he's not here. When DH challenged why she wouldn't do set days she said ' its not convenient for her' but being treated like a hotel at ours is ok or that's her expectation anyway. Basically if DH say black is black she will say its White. Therefore she doesn't want to commit herself cause she might want to make plans however its not reasonable for us to want to make plans....argh gives you head ache doesn't it. As you can see they CAN NOT and don't communicate or have united front

[Kaluki]

Oh dear. Isn't it ridiculous. I can tell that we will have similar problems as my DSC enter their teens as DP and his ex won't communicate either.
At least your DH is firm with him and won't let him call the shots.
Still not fair on you though.

[NorthernNanny5]

Yes luckily DH doesn't Disney parent, but instead we get ex trying to make the rules for us from a far its difficult territory when you get to it