If you happened to be a victim of condom stealthing, don't worry, you can still be safe. There is a treatment called Post Exposure Prohelyaxis (PEP). This involves consuming a morning pill. If it is taken in time, it can prevent viruses from getting into your system, including HIV.
If you suspect that a stealthier has passed on his infections to your body intentionally, then you can approach a physician and ask for PEP straightaway.