4 passages

Hi guys!

1. Nations it may be have fashioned their Governments, but the Governments have paid them back in the same coin. It is unthinkable that any young Englishman should find himself in Razumov's situation. This being so it would be a vain enterprise to imagine what he would think.

--- can you explain to me what the parts in bold mean?

2.

The peculiar circumstances of Razumov's parentage, or rather of his lack of parentage, should be taken into the account of his thoughts. And he remembered them too. He had been lately reminded of them in a peculiarly atrocious way by this fatal Haldin. "Because I haven't that, must everything else be taken away from me?" he thought.

--- does "fatal" here mean that this Haldin had a bad effect on him?

--- He says: I haven't that; what is he referring to? parentage?

3.

He nerved himself for another effort to go on. Along the roadway sledges glided phantom-like and jingling through a fluttering whiteness on the black face of the night. "For it is a crime," he was saying to himself. "A murder is a murder. Though, of course, some sort of liberal institutions...."

--- "go on" here means that he just wanted to continue doing something?

4.

A feeling of horrible sickness came over him. "I must be courageous," he exhorted himself mentally. All his strength was suddenly gone as if taken out by a hand. Then by a mighty effort of will it came back because he was afraid of fainting in the street and being picked up by the police with the key of his lodgings in his pocket. They would find Haldin there, and then, indeed, he would be undone.

--- does it mean that Haldin would be destroyed (undone)?

Thanks