We are saving money for a house.Should I be angry if my bf has been supporting his sisters family?

You should not be angry but you should to talk to him , "how about us". Your bf can help his sisters family but in your situation right now, he should not to help his sisters family because this is the most important to your relationship 'HOUSE' or it depends what kind of help that is very important than your planning to buy a house. Actually , he can help to his sibling family but he should more to support you to save money than his sisters family. House is not simple to save money, that's why you should help each other to save money. You can say to your bf that his sister is her responsibility to do something to her family , not always there some one to help her, she should move about her family and his sister should know and understand that you and your bf planning to buy a house so you need money so thats why your saving money and your bf should stop to supporting his sisters family but not always, just sometimes but your bf should cocentrate to your saving money than his sisters family. Actually , im just 13 yrs old.
I dont have gf. Im too young for that. But still, i hope this can help to your problem