There is something kind of like this, though it's not specific to HIV, and I'm not sure if it's an app or just a website.

https://www.positivesingles.com/

I do think that something more specific for HIV+ seeking HIV+ would be a wonderful thing.

My wife was positive, God rest her soul, so I feel lost now. I would rather be with someone that knows what I'm going through and what she's going through. And I don't have to deal with the stigma of dating with HIV+

It's not a really bad thing to hiv and date another Hiv+ person!