I've always thought of sex as nuclear energy. It's sheer power; it can destroy, or it can build. You can use it to connect in the right context and commitment ( we have a word for that; it's called kiddushin), or you objectify and cheapen. B'Ikar, it touches one's essence; even prostitutes need to deal with "Johns" who develop an emotional connection. But if you're missing context- of what the person is, who they truly are beyond their bodies - you connect only to their bodies, and hence cheapen yourself and them to just bodies. If we express ourselves sexually without having a real emotional connection, our emotions become numb. If we express ourselves sexually without having a real mental connection, our minds become numb.
Pornography and the like of course, have zero potential for connection. And we become numb to emotional aspect of sex, and hence super-sensitive to the physical. A woman in the street is only a body and judged as such (of course, she many also present herself that way); we couldn't care less about who she is. But real tayvah deals with both the emotional and physical; a desire to connect physically in a real way. And it is faaar better; but one must give up lollipops before he can taste a porterhouse steak (which, you can get in Manhattan, they say - though nikur is a nightmare).
The Torah, therefore, was magdir us - to make sure we have a connection before we connect - and we call it kiddushin. Grada, it's not a guarantee; many problems exist in marriage when the connection is happening without connection, but Tzaddikim Yelchu Bo.
So, no, it's not evil, anymore then a gun is evil (NRA, card carrying
). You misuse it, you are doing evil. But it's not evil. Some guy smoked a terrorist driving a tractor some time ago. Guns are great - when used to smoke terrorist.
Pardon my rambling
And hatzlacha on therapy!