First off, it’s against the rules of this forum to advise a minor to go against the wishes of his/her parents. So, while I’m not in complete agreement with the way your parents are handling this, you need to respect their wishes about your friendships.
I think both you and your parents need some educating on Church teaching about homosexuality. It seems that you were never told that homosexual acts (sexual relations with a member of the same sex) are grave matter and, when done with full knowledge and full consent of the will, constitute a mortal sin.
That said, if your father did indeed say this in these exact words:
he is also incorrect. Same-sex attraction is not “practiced,” nor is it sinful. It becomes a sin when a person who experiences same-sex attraction actually has sexual relations with a person of the same sex. However, simply feeling attracted to members of the same sex, in and of itself, is not sinful. Those who experience same-sex attraction are called to live chaste lives.
There’s quite a bit wrong with this. First of all, karma is not a part of Catholic belief. So, while your father seems to have strong opinions about homosexuality, he doesn’t seem to have a spectacular grasp of other Church teaching.
Also, people are not saved “from God”… whatever that even means. Rather, they are saved BY God. So this remark from him is also questionable.
The Church does not require us to shun people who experience same-sex attraction. Since you are 16, your parents are probably concerned that you are easily influenced by your friends and that spending time with them will make you want to have a romantic relationship with another girl. Or they may be concerned that spending time with your friends will give you the impression that there’s nothing wrong with two men or two women having a romantic relationship with each other. And, for now, you need to obey your parents. However, when you are 18 and no longer subject to your parents I would advise you not to automatically sever all ties with people just because they experience same-sex attraction. If being around them is an occasion of sin for you—that is, they influence you to do something sinful like have a romantic relationship with a woman—then yes, you should find a new circle of friends. But I generally don’t agree with cutting all ties with people simply because they’re gay.