Without getting into personal details, my wife and I dealt with a similar issue (not SSA).
Write down everything. Every phone call, every email, every word you can remember. Write down times, dates, etc. Write down names if you have them. Also know that there may be records (arrest records, if she was officially arrested; dispatch computer records; audio recordings of police phone calls or radio dispatch; police report; etc), and some of these records have limited retention. So you want to request them if you think you'll need them.
We filed a formal complaint (typically a requirement for a lawsuit when government is involved), documented *everything*, made records requests for appropriate information, etc. We ended up wining just on the formal complaint (we just wanted the problem fixed - if it wasn't fixed, we'd go for blood). We filed an extremely detailed complaint (around 30 pages; it took us 4 hours to go over it with the agency when we initially delivered it) - I think they knew it would be taken very seriously by a judge/jury if it came to that, and it looked like we were willing to do that.
But, most importantly, I wouldn't even think of doing something like that without my wife wanting to do that. There are risks of filing complaints and such (such as being outed yet again). As for court, it can take months or years to get through a lawsuit - so it's not something I'd do unless I was absolutely committed to going through it. That's one of the reasons we filed a complaint rather than a lawsuit.
If you interact with them, you need to be careful to not do anything that could be misconstrued as threatening, violent, or overly disruptive. Keep the moral high ground so that they can't use anything against you or your wife.
As for lawsuits, I'd only do that if I had no other choice to get things fixed - lawsuits are really, really stressful and take years when government is involved. You may want to contact your state's civil rights office, however - they can go after the rent-a-cops and the rent-a-cops' employer, if there are state laws to protect trans people.
I'm sorry she went through this. My wife's experience devastated me because I know how much it hurt her. I'm glad I thought things through and did things very methodically rather than just letting the you-know-whats have it (which was my instinct - I'd have loved to let them know what I thought of them right at the time).
One thing that I've found that helps is that I go with my wife to things where she's likely to get abuse. They might try to pass her off as crazy if she witnesses the abuse, but having another witness can really help people do the right thing. It's very horrible that the stereotype of a trans person is "crazy and dangerous" but sadly that's the expectation of many people. So that's one way we can help our spouses - we don't carry that stereotype, so we're seen as more credible (yes, that's irrational of the bigots, but it sadly seems to be reality).
