The first thing to do is to stop letting him make you feel guilty and bully you.
This will not be easy but it is essential!
There is no longer any concept of Custody and access or Residence and Contact - it is about how the Care of the children is hared between their parents
It is not for one parent to decide what the arrangements should be - it is for both parents to agree what is best for the children - and if they cannot do so then the court decides the matter.
Your starting point is to arrange to see a Family mediator as a matter of urgency
If your ex will agree to mediate and agree a proper shared care arrangement then well and good.
If not then you will be able to apply to the court to deal with the matter
You are correct the chidlren should be with you rather than a Child minder - and a fully shared care agreement is perfectly viable in the circumstances.
Changing your wording hours may be helpful so that you can have alternate weekends Friday to Monday plus maybe Tuesday to Thursday every week will give equal time with both of you - with you collecting from school on other days as appropriate.
He will object as it will mean no maintenance - but you must not let yourself be bullied!
I hope that this is of assistance - please ask if you need further details