I have fallen for step daughter

From your post it sounds like you're in a shit country with low age of consent. So you probably don't have to wait long.

Woody Allen.

my dad told me he knew someone once who married a woman just so he could get with the daughter and he eventually did. I don't know how it worked for them in the long term though.

Congratulations, you are a sleeze ball. Enjoy yourself.

I would advise you to think this through.
You'd be cheating on her mother, or if you divorced first you'd be breaking her mom's heart. And if you think she doesn't feel the same way about you I'd advise not to do anything. Yes, it will suck, but it will save a LOT of tears.
If you have a friend or family member you really trust (that would't judge you or tell anyone else) and will help you, I'd advise you to talk to them. You'll figure it out.
Good luck.

As long as you don't rape her...

This story reminds me a lot of my life,I to had fallen for my Ex-stepdaughter, her mother and I started to have problems and it was nice having the stepdaughter around we seemed to hit it off,she was fun and attractive,I basically stayed around to stay in her life than came to realize unless she ever deserted her entire family it would never of worked out between us,so I ended up calling it quits ,to this day I still am in love with her, she is 33 now,I knew her since she was 9 but she was 13 when I started having feelings for her and those feelings where not just sexual either

ya nasty

Mental help bro; get some. Sounds like pedophilia. pe·do·phil·i·a
ˌpēdəˈfilēə,ˌpedəˈfilēə/
noun
sexual feelings directed toward children.

You feel your attraction for this girl is wrong, because your attraction to your stepdaughter is wrong... duh.

Here's the thing, you are not blood related and after she is an adult the age boundaries will be at your favor. It is not normal because she is a kid but as long as you don't rape her and wait for her to mature completely then you can be with her.

You might check out Vladimir Nabokovs book Lolita for some insight on this subject.

Well my question to you would be does she do things around you to imply a relationship between you both? Like wear revealing clothes walk around half naked show you her body parts?

1. Get a divorce. 2. Get a psychiatrist. 3. Leave town.

If you aren't in love with the mother then break it off don't stick around just so you can fantasize about her teenage daughter. That's sick, you know you're wrong, don't try staying til she's older you're just trying to sneak into some kids mind and eventually her pants. She's a teen let her date teens, if she does like older men let her choose her own don't manipulate her and don't try romancing her, leave that family before you fuck it up.

Wait till she becomes legal age and go for it.

Although mom might suspect something is up before that happens. Also it might be hard not to sneak in a kiss, feel, sex etc. before she becomes legal. So you might have a problem on your hands.