Job help

hi I would like some advice please.
I work for a non for profit organisation and I love my job. However I feel like I have been Taken advantage of. Back story
I’m a middle manager I have several staff under me and two team leaders. Both of my team leaders left at the start of the year. They didn’t replace them and decided to do a restructure and spilt my role in half and employee another middle manager instead. It took them 6mths to do this so I have been working basically 7 days a week for a 38hr a week pay. I’m in a role that work must be done or it effects a lot of people and customers. The company has now decided to go through another restructure and have decided that middle managers must now work weekends early mornings and late evenings on a rotating roster to enhance the customer experience ie there is a middle manager on duty at all times. The problem is I have basically run myself into the ground ie spent time in hospital as I have been working so much just to keep it afloat and I now feel like they have slapped me in the face as I can’t work those hrs with a small child as daycare centres are not open at that time. Am I over reacting, I feel like I have to go along with the changes just so I don’t loose everything I have worked to build up in the last 5 years.
I already have flexible hrs for them as I run training session at night and can normally get a babysitter as I’m planning & writing them 6 weeks in advance not two weeks out. I also cover shifts on the ground when staff are sick etc and I have to call my mum to babysit but the new structure would see my mum having to pick her up everyday from daycare and also watching her on weekends.
Sorry for the long post advice would great thank you