In relationship with a guy who slept with a HIV positive person. How can I protect myself?

Hi... I know this man.... For so long And he was my ex-boyfriend. I do love him so much... when we cool of at few years. Because I was focus in my study. My friend told me that he got to a relation with one young girl from Dubai and that girl has this HIV. Now it was my problem that we met again and back in our relationship again. My friend just told me lately. But now i was so scared with him to be pass it to me. What should I do to be protected????? Please do help...