It's hard, but it can't be helped. The boy has to learn to swim. And this is the only way she knows to teach him - the way her father taught her, the way his father taught him.
She walks him over to the deep side, promising him all the while that he doesn't need to go in if he doesn't want to, that they're just going to take a look. Then, when he's standing at the edge of the pool, she pushes him in.
He makes a surprisingly loud splash for someone so small. She can see him struggling in the water, trying to come to grips with it. Off to the side someone screams. She pays no attention. She's intent on watching her son. Any moment now he'll get the knack of it, any moment now he'll make that first accidental stroke, then the next, then the one after that. But it's not happening. He's starting to sink deeper. She can sense the panic of the people around her, hear the bare feet drawing near. She mustn't let them hurry her. She must be patient, must give him his chance.
He's not going to make it. Realization and acceptance come together, like a jolt of electricity. As quick as she can she reaches down, grabs him by the heel, pulls him out of the water, the suppressed urgency of the moment giving her more strength than she knew she had. For a moment she is gripped by terror - did she leave it too late? But no, it's all right, he's gasping, coughing. He's starting to cry. He's going to be okay.
She looks up. All around the pool people have stopped talking, are staring at her in horror. She stares back, defiant. It's for his own good, she wants to tell them, he needs to be toughened up, needs to be strong enough to get through life.
After the first betrayal, there is no other.