As you know, the Catholic Church teaches that homosexual activities are seriously sinful. Pope Francis made that clear in his most recent document on the family. That teaching is not going away. The Church also teaches that all people should be treated with dignity and understanding. Notre Dame is a Catholic university that (mostly) takes seriously its Catholic mission. If you come in with a chip on your shoulder and the mistaken assumption that you will be singled out as a walking bag of sin (because we are all walking bags of sin), you’re not going to have a good experience. If you expect the university and ALL of your fellow students to regard homosexual activities as perfectly acceptable, as though you were on a secular campus, you’re not going to have a good experience. But you might be surprised to find that most of your classmates will be completely accepting of you as an individual, and really won’t be interested in your sexual orientation, unless you constantly make an issue out of it. Most of your classmates either don’t understand or don’t agree with Church teachings on homosexuality anyhow, for what it’s worth.
It can be a mistake to base your college decision on what a handful of unhappy students post online – for example, no one is “forced” to fight for LGBT rights, and it’s your choice whether to allow yourself to feel excluded from the ND family. All students are part of the family, which is one of the things that makes ND such a special place.
So it’s really up to you. There is a University-sponsored organization for gay students, but it operates in accord with Church teachings. If that isn’t what you are looking for, then you are wise seriously to consider enrolling elsewhere. But if you fell in love with the school on your visit, it might be exactly the right place for you.