I do feel like, in my own life experience, that anniversaries of loss and grief are very powerful. I can relate to feeling like you want to do something to mark the occasion and to have a different relationship to this part of your past. However . . .

It sounds like you have been asked not to contact her further. If you have, I think it's important that you don't. If she knows it is from you, she will be able to explain to others why it is from you, and the anniversary date will be something objective to point to.

No matter how much someone has hurt you, it's not right to continue to contact them after they've asked you to stop. People who don't respect the wishes of others are sometimes subjected to criminal charges and/or court protective orders. Either one of these things could have a negative impact on your future in terms of jobs or social relationships (i.e. people looking you up on the internet and finding these things).

I don't think that continuing to contact her, including this anonymous plan of yours (which really just makes it look like you know that contacting her is wrong, but you are willing to do it anyway), will not end up helping your case. It will make you appear to be the kind of client that no one wants to have, will demonstrate a reasonable basis for terminating you, and would generally make you appear untrustworthy and vindictive. In general, people who file complaints against others, T or not, do not continue to try to contact or have a relationship with them.

I don't think anyone is entitled in the way you describe yourself to be. Your great pain doesn't justify contacting someone who doesn't want to be contacted. You will not demonstrate your pain by sending anonymous poetry; you will instead demonstrate that you will not respect boundaries. And it seems unlikely to me that this will assist you in demonstrating that your T was improper to terminate you.