Byron1122, I'm sorry that you had the experience that you did because it is considered a legal crime to expose a child to p 0 r n o g r a p h y.  In every State in the U.S., it is considered child abuse to expose a child to p 0 r n - still photos, video, and written p 0 r n o g r a p h i c prose.

Although I've heard many arguments that support p 0 r n as "normal," I am steadfast that it is typically (typically, now) objectifying and doesn't portray what a normal, healthy sexual relationship consists of.  The argument generally begins with other cultures that actually have children sleeping in the same living space as their parents who are having sex, and this isn't p 0 r n.  Sex is a natural, normal, and healthy aspect of a relationship.  What a child is exposed to at that point is what is acceptable/tolerable/expected in a relationship, and most cultures hold to an expectation that the couple will be as discreet as possible.  The difference with p 0 r n is that it typically depicts the obejctification (use, abuse, discard) of women in very painful and risky sexual situations that do not generally occur in a typical relationship.  Today, girls are unable to view themselves as anything more than objects without any more importance than a disposable lighter. 

Now, the reason that p 0 r n is unhealthy for children to view is that, as I typed, it is typically unhealthy visual information about sex, and that children's brains have literally not developed enough for them to process what they are seeing.  They do not have the experience and maturity to process the visual information that can (depending upon the material) actually taint their perceptions of what healthy sex is all about. 

I would urge you to work on rewiring your thinking to understand that p 0 r n o g r a p h y usually involves paid actors to engage in acts that they would never do with their partners, and they're doing it for a sum of money - much like a nail technician will give someone a manicure or a roofer will place shingles on a roof.  p 0 r n does not represent safe, healthy, loving, and respectful sexual interactions. 

Best wishes to you.