Wow dude, I know exactly how you feel.
The same thing has had and still been happening to me, even up to this day. The worst thing about it though is that I have to deal with TWO brothers, one’s older and the other little. I’m not going to lie; I hate the both of them because of their successes.
Growing up, I had to deal with the girlfriends my older brother was getting from time to time. He was no womanizer, but he somehow managed to obtain some of the prettiest women I’ve ever seen, which is mind-boggling, because he’s much less physically attractive than me (he’s also fat), but he’s a musician and that is guaranteed to make him a chick-magnet; musicians make a lot of money after all. Currently, he’s married, settled, has kids and still is overweight. Not to my surprise, his wife is attractive, although she is very hot-headed; they’re also constantly fighting.
My little brother is the complete opposite. He has a fairly normal male physique and has an outgoing (I call it obnoxious) personality, which is what guarantees him to attract the girls. I’ve actually lost count of how many girlfriends he’s had throughout the years. He’s a natural born womanizer and to this day, he’s still getting girlfriends and getting laid like a breeze. Unlike my older brother however, he’s very dumb and accidentally had a kid with one of his many lovers (it's her fault too) and works day and night to make sure his kid eats.
This is probably going to make me sound stupid, but I’m really envious of their lifestyles and I wish I was more like them. It’s not a big deal right now, but later in my life, when I’m 30, 40 or 50, I’m going to be seen as a freak of nature.
I’m going to have to deal with them like this until my lonely deathbed.