With regards to your brother. It seems clear that you do a lot of comparison to him and I won't judge but suggest something.

my brother, whom I do not associate with and haven't for over 20 yrs is an arrogant b*rd. He was the one in the family with outgoing charisma, and to all that worshipped him, an unblemished personality. To them, he could do no wrong. He too was popular with almost everyone he met and had many friends, could have had many gfs if he wanted but chose his HS first gf to marry, have kids and go on with life. That's his good point, and he does have them. Although personality wise I really do not like him, I respect that he probably has some good points too.

With regards to being the introvert in the family the sensitive, emotional brother, it was hard growing up in his shadow. I understand how this affects you. Please don't misunderstand.

The idea to get away from this is a sound one. I know it may not be possible but the more you are near your brother and interacting with and around him, the more this shadow is going to feel overbearing and it does, indeed, make you question who you are, what's wrong with you, etc. Getting away, making your own way is the toughest and most amazing thing you can do for yourself. I know. I did that about 20 yrs ago. Not just my brother but family that set my role to one I did not want to be in.

Mind you, finding my independence, and myself and where I fit in, was not one that entirely happened until I was separated from my 2nd wife almost 5 yrs ago. Many times we have to be forced to get out of the situation we're in, forced to deal with things in a challenging way that we don't do on our own. But I urge you to take it upon yourself to make the change before life forces you to do so. Be your own person and that will take beign out of his shadow, maybe even for a time, cutting him out of most of your life and keeping things cordial but distant.

I think being on your own will do you wonders. I am an introvert. I now have no relationship or gf or anything. My ex (separated wife) lives with me, under my "care" (logn story) and I have two teen boys. I can now stand up for the most part to my ex who bossed me around for 14 yrs, I have no qualms about going forward in life on my own even though a gf would be nice to have, I don't need it and am my own person for the most part. This all came from being forced to be a single father alone, dealing with it and coming to terms with who I am.

I have no suggestions on how to do this but I will say find a way to get awy from not only your brother, but your family dynamic and as you find yourself, accept your personality as a good one and find value in your own role in life, you will gain confidence and find more women attracted to you.