That's a boy. Females can't flare their girls like that. Also on such a light pigmentation the eggs would be obvious. Looks like you got a pretty PK boy :)
Who am I? Well I am a Junior Member of the International Betta Congress and a breeder of white HMPKs, red dragon HMPKs, black/red dragon HMPKs, metallic multi HMPKs, blue masked HMPKs, and now multi color HMs. Soon to add black HMs. I will be showing in New Breeder class in fall of 2012.