Is it alright for my bf to talk to a girl he once liked and she liked him (they use to send nudes)?

[Melina]

My bf told me how him and this girl use to send nudes and stuff and he really liked her, now they're talking on BBM and twitter.

I feel like that's weird to talk to someone who you hard string feelings for while being with someone else.
He hates it when I text people that like me so what makes it different? From what he's doing?

I told him I'll start talking to someone I use to send nudes too...