Main Carer

I am looking for some advise.
Two years ago after my ex wife an me divorsed.
She made life difficult for me to see my children. To the degree she accused my father of sexually abusing our 7 year old daughter. This went through social services and court . This backfired on her as it was proved that she was playing games with her mind. I eventually have shared residensy with her. I now have the problem of her playing games where it comes to ther social and education.

Our daughter is behind with her work at school. I suggested to my ex that we could help her with a private tutor. Which i have carried through and she is doing well with not only her education but her confidence too.
My response in essence was you sorted this out you do it yourself. I can do this but it would be benificial for both parents to be involved. I put her in to brownies again the same response. SHe has events to go to and she refuses and makes exuces that she cannot go.

I just feel like i am the one looking out for thier education long term and them being ready for thier next challenges in life now and in the future.

I am not saying she is harming the children but her sheer divide of thier lifes are not a benefit not only to our daughter but our 11 year who is about to start high school.

She has entered her forth relashionship since our divorce which I dont think is helping?

I dont want them to stop seeing thier mum but thinking they may need more time with me to support them.

I currently have 6 out of fourteen night with them.

Can you advise