I'm going to assume that you are not much older than your brother, that you are still in your teens. Puberty is a time when there are many things going on physically, mentally, and spiritually. You are in your formative years. Adn it is easy to get influenced over many things. I already see that you are being influenced by your brother as your are starting to have these feelings as well.
The Bible unequivocally states that Homosexual relations are a sin. Many will argue that people are born homosexual, but I would argue that these are spiritual forces all around the lurks to destroy people in not just homosexuallty, but any kind of deviant sexulality, any form of sin that these forces beleive will best attract their victims. The Bible says that Satan goes to a fro seeking to whom He may devour (I Peter 5:8), so those who are weak in faith are particularly susceptable.
If you read this thread, you'll see an extreme case where someone who has had nothing but heterosexual feelings sudden being tempted into homosexuality:
http://www.christianforums.com/t2656320-my-story-with-my-bizzare-neighbor.html
The point to remember is that there is no temptation that is not common to man:
"There hath no temptation taken you but such as is common to man: but God is faithful, who will not suffer you to be tempted above that ye are able; but will with the temptation also make a way to escape, that ye may be able to bear it." - I Cor. 10:13
But God promises a way fo escape. Paul had a struggle in sin in Romans 7. We need to run to God and fall on our knees and admit our weakness over whatever temtation we have and ask for God's Spirit to break the hold that the sin has of us. See how Paul followed up with Romans 8:
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There is therefore now no condemnation to them which are in Christ Jesus, who walk not after the flesh, but after the Spirit.
For the law of the Spirit of life in Christ Jesus hath made me free from the law of sin and death.
For what the law could not do, in that it was weak through the flesh, God sending his own Son in the likeness of sinful flesh, and for sin, condemned sin in the flesh:
That the righteousness of the law might be fulfilled in us, who walk not after the flesh, but after the Spirit.
For they that are after the flesh do mind the things of the flesh; but they that are after the Spirit the things of the Spirit.
For to be carnally minded is death; but to be spiritually minded is life and peace.
Because the carnal mind is enmity against God: for it is not subject to the law of God, neither indeed can be.
So then they that are in the flesh cannot please God.
But ye are not in the flesh, but in the Spirit, if so be that the Spirit of God dwell in you. Now if any man have not the Spirit of Christ, he is none of his.
And if Christ be in you, the body is dead because of sin; but the Spirit is life because of righteousness. But if the Spirit of him that raised up Jesus from the dead dwell in you, he that raised up Christ from the dead shall also quicken your mortal bodies by his Spirit that dwelleth in you." - Romans 8:1-11
We must abide in God's Spirit, We must abide in Christ for His spirit to be made manifest (John 14:21). We must be willing to obey God.
God has given us His Word that we may be renewed in our minds (Romans 12:1-2) and that we may immerse ourselves and be cleansed from sin (Psalms 119:9-11) .
God's Spirit will operate according to His Word and our obedience to it. Jesus saved us from our sins and He saved us from the power of sin ath it may not have power over us.
You have to forsake these feelings and implore you brother the same. Nothing is too late. God is able to save you from you sin and the power of sin. But you must act upon it quickly lest that sin become so strong that you becomse so wrapped around it that it would be more difficult to break. But where sin abounds, grace much more abounds.
Seek God quickly, is my advise to you, my friend.