Look, you may think you have earned your place but quite frankly without a solid and committed marriage, you don't have jack or squat. And even WITH a committed marriage, that STILL doesn't make you this poor kids father. You can be her friend, you can hold her when she cries and tell her you love her, you can help raise her and help her become a great person who has the strength to rise above strife, but you STILL will never be her father. That's just the reality of being in relationships with people who have children that aren't yours. You can't just sweep in and decide you're better and that's that. Esp when mom already tried to pawn the child off on man number 2.
My husband has been my daughters "father" for nearly 8 out of the 10yrs of her life. Her own father walked away several times, and at one point walked away for 3 yrs without a single word. He's only been back consistently for the last yr or so. My husband raised her, loved her, cared for her, supported her, PAID for her when her own father said he would rather remain unemployed than pay me ANY child support, and did everything a "father" would do for his own daughter. That still didn't make my husband her father and until a judge says so, he will never be her father. But even with him not being legally her father, it was never lost on my daughter who the person that took care of her was. She loves her father, but when the chips are down its my husband she turns to. There is no piece if paper needed. You need to sit down and have a serious talk with yourself and understand that paper documents aren't what make a father. If you stay and end up being there for the long haul, then you will have secured your place in this childs life with or without being legal. At the end of the day, that should really be what's most important.