Everything available to your brother was and is available to you. You are pointing to his successful relationship as if it were a roadblock in yours. When we are jealous of something someone else has that is good — it points toward our own limitation — not their success.
You state your age as 26, so it is time to reclaim your individuation. Rather than focus on what you brother is or isn’t doing, it is time to turn the attention inward. Resentment is an insidious emotion. In fact, such organizations like Alcoholic Anonymous (AA) have specifically identified as the “number one” offender. Yet, researchers are just learning more about its mechanics. What we do know is that when there is resentment someone, in some situation, has seemingly taken away our freedom.
The key word here is seemingly. In their book, The Resilience Factor: 7 Keys to Finding Your Inner Strength and Overcoming Life’s Hurdles, Karen Reivich and Andrew Shatte, apply the best of todays work on how to manage our negative emotions by offering techniques to deal with them. One particularly important section is on thinking traps — common patterns of thoughts that prevent us from seeing a situation accurately.
I would first get a copy of this book, and then look for a therapist to help you sort thought this difficult feeling and help transform it. Check out the find help tab at the top of the page for a therapist near you.