It is definitely possible to hide, after all, you almost have an option of what you want to be, as long as you don't tell anyone no one will ever find out, and no, it should not mess with you mentally, because no one is entitled to know what your sexuality is and you do not need to tell people. It is absolutely fine.
Just consider the fact that many gay and bisexual men felt exactly like you at one point, me included, and you will most likely come to accept and embrace it eventually and realise it isn't bad at all.