HIV & homicide??

My husband has all the signs of HIV and we have an open relationship. He says if he has HIV he's going to kill himself and me? Can't tell if he's just being dramatic or? Idk. I find that very concerning and almost don't want to get checked just in case now?? But also he never has threatened me before and we have a wonderful relationship outside of this one comment??

He says it's my fault for opening up the marriage, but he's the one who wanted that and kept talking to people outside of our marriage so I made it happen for him... I couldn't live with myself if I made this happen to us so naively. The rules were the other person had to have an STD check. I don't understand how this couldve happened. What will happen to our daughter? How easy is it to spread to her?!

Update: We do have potential partners have STD checks first. But his long term partner also has sex with other people since then.