One - proceed as he had before - storm away from number four when he heard Mundungus Fletcher disapparating, find Dudley, stalk about the the local area until they were attacked, defend them from the dementors, then deal with the consequences. However, he was acutely aware that there was no guarantee he  would  be able to defend them against the dementors - how could he possibly conjure a patronus in his current state? The memories that had once brought him such pleasure and joy were now tainted by heartbreak and sadness. He woke, more mornings than not, gasping and holding a sob in the back of his throat. And then there was the ministry to consider - Draco had made it abundantly clear that there were no guarantees in this new life - he could end up getting expelled for real, and then where would they be?