Libbylou, you are not responsible for the actions of your ex-husband. If that had an effect on your daughter, then that is on him. It makes sense this would affect her but there is probably a lot more at play, some which you might not be aware of.
Stay way from blaming the spouse for enabling. He is supporting, no doubt is part of your daughter's care team, and has a big load to carry as the primary support of your daughter. He deserves credit for the hard yards he is doing here, not to be accused of enabling. It's not his responsibility to fix your daughter but to support her as she does the work to get better.
Your daughter has a mental health team and they know she has a daughter. Mental health teams usually work with the whole family unit. They may be in contact with the school regularly already and may be watching things. I don't know how it works in your area though, so can't assume.
You said you are in pieces tonight so this is not the best time to be making that decision. Wait until you have calmed down. Then make the best decision that is right for your granddaughter, keeping in mind that professionals can probably hear you out but can't offer any feedback or information to you.
When you are ready, give some honest thought as to why your daughter might have backed away. She might just need some space, it might be because of her condition, it might be because you have pushed too hard or got too involved or the husband has felt judged. I know how hard it must be not to get very involved, you're her mother and love her and want to do anything you can to help her. That might not be the role that she wants you to have though, as hard as it is for you. It's hard to be a mother and see our children struggling. Some professional support for yourself might be good and might help you work through the decision of whether to contact someone further for your grandchild, or not.