I need some advice, My husbands children are hard to read, i think their mother may have manipulated them so much over the years that she has messed them up.

They have the strangest behaviour towards their BM borderline obsessive with her, I will try to explain as briefly as i can,
We have EOW access and yet the BM still has them both days for their horse riding so we have them at night, yet she still rings them every single night despite spending all day with them, sometimes 3 or 4 times, now if she doesnt ring the kids are constantly checking the phone for missed calls, ask if they are allowed to call mum! asking each other why hasnt she called yet?
Now she has a new boyfriend all her phone calls have stopped (thank god i say)

However, when they are on the phone with her they yell at her because she has gone out or because she is lying about where she is, the kids blatantly tell her she is a lyer and they openly call her a stupid bitch and a mole SS10 always calls her names to her face. As per a previous blog SS13 has sent her texts calling her a Fat Fuck.

A bit of history - BM has told these kids to abuse me and my son
she took the kids off DH when he met me, she tried her best to get the kids to hate us, told them lies and i believe she has guilted them into feeling like she is the one that is so hard done by, she tells the kids DH doesnt give her money (she gets a LOT of cs)
When she has had boyfriends in the past the kids ended up living with DH full time until he met me anyway. She had another baby prior to DH meeting me and asked him to be the father cos the actual father had the sense to disappear. SS13 (then 10) stole things from our house and she thought it was hilarious.
Honestly these things are just the tip of the iceberg.

I believe that the kids are seriously damaged. I dont know any other kids to behave the way they do, i dont know anykids that are constantly calling and texting their mother or wondering where she is or what she is doing. And then ringing us and asking us to live with us because they hate her so much but then everytime they talk to her on the phone they end with "love you heaps" even though saying that seems more like habit because thats how they end all phone calls.

I think that they have been so manipulated and guilted into feeling responsible for her wellbeing because i have no doubt she has spent years of making out that DH is the bad guy. I think she has messed with their heads so so badly.

Does anyone have some insight? or does anyone else have kids like them? My BS has 50/50 with my ex and he could give a rats if or when he hears from me or his dad. He is a normal 12 year old.