Verified answer

No he left after he found out he wasn't Amy's biological dad. He drove a car into a frozen lake with Amy and Roxy inside. Ronnie rescued them and then Sean emerged from the lake and Roxy told him to leave.

No he didn't. He left. This is what happened - On 1 January 2009, Sean gave Amy to Stacey and asked her to look after her for a few days, but she couldn't do it and gave Amy back to the Mitchells. Sean returned to the Vic and convinced Roxy to leave with him and Amy, but drove them to an icy lake with Ronnie and Jack in pursuit with the intention of driving into the water and drowning as a family. Roxy quickly got out of the car but Amy was still strapped in. When Ronnie and Jack arrived, Roxy coaxed Sean out onto the ice to allow Amy to be rescued. With Ronnie and Jack watching, the ice broke and the pair go under. Sean freed Roxy from the weeds in which she was entangled as Ronnie dived into the water to rescue her. Roxy and Ronnie escaped the frozen lake, but there was no sign of Sean. Roxy saw Sean crawling out of the water while Ronnie and Jack were warming up back at the car. She urged him to flee, and Sean walked away into the darkness.

If he wouldn't of flee'd, he would of been sent to prison.

That's the official story of what happened.

Hope i helped :)