If this is legit…I think an important point is that the son made a well-reasoned, mature decision to pursue a double major that took 5 years and may help with future income. This is different from a scenario in which a parent has to pay a 5th year due to partying or non-performance in general (and some of the latter situations are not the kid’s fault either.)
I would not expect a kid to pay back in the current economic situation with high living costs, unless his pay is high or if he lives with you.
As for the original post as a whole, there seems to be some anger and jealousy involved and I would suggest - strongly suggest- counseling.
The fact that some on here think the post is not real, tells you how unusual your post is and I think getting some help with your feelings will help clarify the financial issue.