PEP (post-exposure prophylaxis) will make it much less likely for you to contract HIV, but you must begin taking it within 72 hours of potential exposure, and the sooner the better.
If you’re in the US, this CDC page has more info about where to find treatment.
A doctor will be able to tell you what other tests you should have, but I imagine they’re going to just want to screen for the usual stuff (chlamydia, gonorrhea, etc).
Do you think that if the prosecution made a secret deal with the witness, a deal that the jury didn’t know about, would that make another trial or reexamination of evidence necessary? Because that’s what happened.