The only way any of them had any hope of ever being truly happy again was to risk that he might be caught going for her. I think that other possibility (a life without Elizabeth) was so unthinkable for him (for himself or for any of them) that it was really a non-choice at that point in his mind.

I agree. As jae said, it's kind of a big blob in his mind. He isn't just saving Elizabeth because he's madly in love with her, he's also trying to keep his kids' life in tact for their own happiness. It's a gamble, but one he's prepared to make and has reason to think he might pull off, so it's worth the risk. (Much better a risk than The Clock caper!)