Can a former supervisor email a late performance evaluation to you at your new job and copy your new boss?

I left a bad division in March of 2012 and went on a 6 week medical leave because I was treated very badly, I was even hospitalized for 3 days before I went on the leave. Fortunately I was able to transfer to another division. When I left I hadn't been given a performance evaluation which was due late May. However I started my new position in May and have been there 3 1/2 months under a different manager and things have been great working here and so much better. I was putting all this behind me. Then yesterday the other manager from where I worked before emailed a late performance evaluation to me and copied my new supervisor and told me to sign it and give it to her (my new boss). The evaluation was negative of course ("needs improvement") and a lot of bad stuff was written about me on another document that corresponds to the eval form and it made me look like an inept idiot that couldn't do her job. Isn't it unethical for one thing to just "email" a negative evaluation to your new job 2 1/2 months late and copy your new boss? Doesn't that make the evaluation invalid? Just the fact that nobody went over it with me and allowed me to give input was wrong. But I had already transferred out before the evaluation was due. I know this was done in retaliatory measure. Now I have to "explain" this to my new supervisor today. She knew some of what happened but not all of it. I wanted that to be behind me. Now she knows all of the stuff they said about me that were lies, twisted fabrications. I can appeal it. But I was told by a former co-worker that they could make it worse for me if I don't just sign it.