Meaning
The chiefly British idiom, feel hard done by or feel hard done-by means "to feel treated unjustly/unfairly". The meaning is not akin to a feeling of betrayal.
Usage
In the idiom, hard done by is an adjectival phrase. So, on further thought, I think the following construction would be grammatically incorrect,
He felt hard done by by former friends.
because it implies the subject complement and the auxiliary can be inserted thus:
He felt he was hard done by by former friends.
This usage is improper, as it treats hard done by as a participial element, which it is not. While some may parse this differently to argue for its correctness, one would be hard-pressed to find the idiom ever used in this way (followed by by). Rather, it is used by itself or in conjunction with an adverbial. I give several examples:
I felt a bit hard done by, going through that rough patch.
They certainly felt hard done by at having their privileges revoked.
Feeling hard done-by, mate?
He tried to cheer me up, but I couldn't help feeling hard done by.
She felt hard done by at having to do the chores while everyone else went to play.
Poor Cinderella must have felt so hard done by when her wicked step-mother
denied her permission to go out.
No need to feel hard done by, bro. Every dog has its day.
In your final example, the correct choice would be:
The situation made him feel hard done by.
Prevalence
This idiom is not a Canadian regionalism or colloquialism. It is mainly used in the UK and other English-speaking countries of the Commonwealth, which includes Canada, Australia, India, etc. As such, it is more widely used by non-US speakers.
Best Answer
I use it to mean "okay?" or "right?" or "do you not agree with me?" All more-or-less the same, acha?