A lifeguard would be able to save her without letter her pull him under. Any way to do that, or do you have to abandon her and just let her drown?
How deep is the water?
As long as it is over your head, it doesn't matter if it is 15 ft or 1,500 ft. You will still drown.
Or if it's 3 feet you can just let her stand on her own when she figures it out. She's not going to die if you let her go. But you do need to take care of yourself first. Her problems are her problems.
If you try to rescue then she is focused on fighting your efforts. Let her learn to swim for her own benefit.
M22,H45,W45 S21/18D12 Retain faith that you will prevail in the end, regardless of the difficulties and at the same time confront the most brutal facts of your current reality, whatever they might be.