Mom's BF might be catfishing me

umm ok my mom's been with her BF about a year and he lives with us. He's a really good guy. But I think him and mom haven't been getting along as good lately and him and I are like pretty close like friends but also dad/daughter kinda. But sometimes it feels a little flirty with him, ig? I'm not all that popular at school and so I don't have a lot of experience like noticing flirting. Lately though I've been talking to this guy online that I thought was a little older than me but seems really mature and the other night he sent me a pic in his boxers and um, it kinda looked like our house like our carpet but it was hard to tell. I kinda wonder if it's actually him. I don't want to hurt her and tbh I've really been enjoying having someone to text and stuff and im really starting to like him but idk what to do.