Can a former employer lie to me and tell prospective employers something totally different?

At will means you or they have no obligatory contract over the job. If the employer fired you at will but tells others it's because of your race or creed, then that would be an admission of discrimination. If you had been fired because of your race and the employer tells others that you are a person that should not be hired because you file complaints, that is retaliation for the discrimination complaint. It would bring more discrimination complaints on this employer, only if your termination was due to discrimination complaints. If the employer tells others you had been fired because of poor work and doesn't recommend you, there is nothing you can do but tell your side of the story or find an opportunity where they don't call employers. Gays are not protected under federal anti discrimination laws or acts. An employer can fire you if your gay with out any legal trouble. Some states have laws to protect gays, but employers don't say it's because of being gay and there are probable no cases where a gay ever won.