My name isXXXXX a licensed attorney. Glad to try and help out.
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. Retaliation is a serious matter and such conduct is prohibited by the Notification and Federal Employee Antidiscrimination and Retaliation Act of 2002, to mention one of the main provisions. Likewise, both hostile workplace rising to the legal definition as well as age-based discrimination over age 40 are both forms of unlawful discrimination.
Here's the botXXXXX XXXXXne. There is a mechanism in place, and you can (and certainly should) proceed with your discrimination (equal employment opportunity) charge. This is an exclusive remedy, meaning you must follow this process first, rather than going directly to a lawsuit. You have more than enough solid reason to proceed here, in my estimation.
And, as far as your mention of legal counsel, I commend you for being astute in this regard. You cannot be forced to proceed without legal representation. You have a clear right to have counsel of your choosing. This is not a paid "right to counsel" as with some proceedings (i.e. indigent criminal defendants), but if you pay for an attorney you absolutely have such a right. And, if you have any concerns about the investigation process, you should not hesitate to contact the Office of Special Counsel as well. I would absolutely encourage you to have an attorney for the mediation session if at all possible.
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.