Student Exchange Programs

we have this exchange student staying with me and my dad is so nice to her like he puts on a really nice voice and acts like they are best buddies and then when it is just me and him he asks me why I am there in a nasty voice and says I am acting like a dork.He is acting normal again cause the exchange student is hanging around him but what should I do about it? you might think Im overreacting but I got really upset when he called me a dork.
The reason he called me a dork is cause Im reallyshy and I was kindof stooping…but him calling me a dork made be lack even moreconfidence.Im almost crying at the moment.I think he hates me.Im also scared of him cause he has moodswings.I told my mum but she cant do much abouut it cause she is at work all day.