Was he usin my phone?

I live with two gay men who r currently seperated . One of them has a laptop I have an android that I use for the wi fi and we share wifi. I think one of them went on my droid because the web history on my phone has gay websites and gay craigslist personals ads. My question is, can we see each others web history since we share wifi? Meaning im seeing his history on my phone, or did he have to use my phone for it to show up on my web history? ? I just don't want to bring it up if im wrong