Thanks for your courage in making yourself vulnerable by pouring your heart out. I, too, am a same-sex attracted Catholic. We are very, very fortunate to have at our disposal the very presence of Christ through 2000 years of tradition and teaching and orthodox reading of the Bible...
You're right. It would be wrong to marry a woman. It also would be wrong to marry a man. It would be wrong to have any sex whatsoever with anyone outside of marriage. It is also wrong for us to have sex with ourselves. And most of all these days, it's wrong to use porn and to masturbate. If this is or becomes an issue, check out NoFapChristians here on reddit.
Don't try to justify "gay" sex. It's contrary to God's creation of our bodies. Check our Pope John Paul's "Theology of the Body". Also check out Cardinal Ratzinger's (Pope Benedict XVI) "Letter to the Bishops of the Catholic Church on the Pastoral Care of Homosexual Persons" (1 Oct 1986). The letter was controversial because the phrase "objective disorder" was used. But this is a philosophical way of speaking that refers to same sex activity as having the wrong object in a person of the same sex. Disorder refers to the good order of God's creation that is being perverted.
I like the phrase same-sex attracted rather than gay. Gay means that you are adopting your sexual orientation as your identity. But one's sexuality is not one's identity, it is only a part of who your are. It is far from being the most important thing about you. You are same-sex attracted but not gay. Your identity is Catholic Christian, in Christ an adopted son of God.
Your life will not be lonely. You will have intimate friends. You will be involved in the lives of others. You will have spiritual intimacy with Jesus and Mary. The saints will inspire you. Mass will keep you focused. You will pray. You might even read the short letter of Paul for sustenance (Galatians, Ephesians, Philippians, Colossians).
Pious homosexual men (that too is a much better word than "gay" in my view--homosexual)...have always been the backbone of the priesthood. Consider becoming a priest! You could either serve in a parish or you could live in a religious community as a priest, say a Jesuit or Franciscan, etc. A tiny number of Catholic men are called to monastic life where they live in monasteries and devote themselves to work and prayer. And they are joyfully at peace.
Don't let all the lostness of modern society lead you astray. Look at the big picture of 2000 years of wisdom and truth and an eternity that awaits us!
May God bless you as you seek His will. I can see that already He has blessed you immensely. You have a lot to offer the world...