How do i deal with a pain that my dad left?

my dad left us when i was 9 or 10 years old. now that i am 16 he rarely visits us. A few months ago he got himself a girlfriend that has children our age.But a few months after that he told me if i would like it if i had a half sister. i jokingly said that i do not care but i did. i was thinking what he meant by that. and also how could he have more kids when he cant take care of us and he took away our old house and made us live in the shelter. i used to cry at night and say how sucky my life is..