My name isXXXXX'm a licensed attorney. Glad to try and help out.
Many thanks for your patience in writing back and forth!
Sure sorry for your circumstances, truly. My heart goes out to you.
Here's how this works, having read and carefully considered everything you're shared. Kudos to you for being proactive and speaking with Human Resources about the issue of severance pay. Likewise with demanding that your review be corrected. Now, I think the main issue here centers about a potential violation of federal law. There is a ton of misunderstanding, but here's the botXXXXX XXXXXne. It is indeed possible for an employer to lawfully terminate an employee who is out on leave. Here's the official explanation, along with examples:
29 C.F.R. § 825.216
However, and this is a very important caveat, an employer (not the employee) bears the burden of proving that the termination decision was not related to the leave. In other words, your employer would have to show that you would have been terminated without regard to your leave. That's not at all a given, and in all candor the course of conduct you're described does raise cause for legitimate and valid concern.
That's an overview of the applicable law, but in terms of seeking redress there is also a remedy afforded by the Family and Medical Leave Act of 1993, Pub.L. 103–3, 107 Stat. 6. I'm speaking of seeking help, free of charge, from the United States Department of Labor Wage and Hour Division. Given what you've described here, you have more than enough reason to do so. In fact, I've seen instances where the mere mention to Human Resources (letting them know that you know your rights and aren't afraid to exercise them) will rather quickly result in their willingness to do the right thing. The way to do so is to contact your regional office (for these matters it's done this way rather than through a centralized system in Washington, D.C.), which for you is as follows:
Denver Colorado District Office
I would recommend going that route, although the law does provide an alternative means by way of submitting your complaint here:
Acting Secretary of the Department of Labor
There is no form promulgated for this purpose, meaning a simple letter with pertinent information and relevant dates suffices.
Now, hopefully it won't reach that point, but I would just mention that if the matter isn't resolved at the administrative (regulatory) level, there's also a private cause of action, as follows:
So, that's about the size of things, and I know it's a lot to take in.
Please know that you deserve to be treated properly. I hope you see justice accomplished.
If you have a follow-up question or need clarification, please just say the word by using "reply" to reach me.
I truly hope all works out for you and that things look much brighter down the road. If you do need to write back and I've logged off for the evening, you have my word I'll be sure to check back for any updated word from you tomorrow (Monday)