I know it's easier said than done, but you could try to compare yourself to who you were in the past ? Once we start thinking about your past successes and acheivements, our self-esteem is boosted. Also, you may be "idealizing" your brother, like, okay, he may be a very kind and talented person, but he's human, which means not perfect. Remember that he has flaws too ^^ Same for you : ocne again, I know it's not easy, but you could try to keep in mind that you are awesome as well, I mean, you have lots of strenghts and abilities too, even if you may not be paying attention to them.

In other terms, everyone is equal. We all have our weaknesses and our strenghts. It's not because you are imperfect that you are not amazing~