How do I deal with those people?
If you're not related to me, you are now an aquaintance. I see you by chance, and don't provide any opportunity for you to leech off of me.

If you're family, in this case its my sister, I invest nothing, expect nothing and also I keep you at arms length. We are not buddies, we are not friends and me listening to your *****ing is a rare event.

Don't feel bad, this "friend" of yours has bled you dry and one sided relationships are never worth it.