I haven't left my Church, and my faith is still fine. I will say, though, that often other people can be discouraging. I think that within churches that have a stronger institutional presence, like Catholicism, the effect of discouraging people can be multiplied because human foibles can become institutionalized. That's ... frustrating. Exasperating. Sometimes infuriating.
I've come to see that's the case with all human institutions. You should see the institutionalized inanity of universities up close. For me personally, that doesn't mean that I would abandon the idea of higher education, or even the institution of the university. I think most of the time one can do more good as the rebel and conscience within the Institution who holds on to the ideals and values. Not everyone agrees, and I have faculty colleagues who leave for industry and research institutes and other endeavors from time to time.
In terms of "coming out", I hope you'll find that within the Catholic community that it's much less traumatic than it is within our more Evangelical Prostestant brethren. Expect older relatives to worry about you and pray for you, and occasionally annoy you with sideways comments and "suggestions". Expect peers to be understanding, or to argue for fun, but not to shun you. There are a lot of "fallen away" Catholics, after all.
To some extent, people will make as much of it as you choose to make of it. If you start hammering away about atheism and wearing it as a badge, you'll get more response. I suppose sometimes that's what people are really looking for when they "come out", since the purpose of coming out seems to be to declare their independence publicly rather than just going about their own life in a different way. So I think folks' reactions depend a bit on what you're looking for and need as well.