There was blood upon his hands as well as other guilt.

If he were caught he must die, or at the very least be imprisoned for life.
He could never again be free to come forth after the expiation of his crimes and to claim her and his child.

If he escaped now, it must be to live in a distant country under a perpetual disguise.

If he were caught, the news of his capture would be in all the papers, the news of his trial for murder, the very details of his execution.

The Ambroses would know and the squire, even the country folk, would perhaps at last know the truth about her.