She isn’t interested in you. You’re sabotaging yourself by staying with someone who’s not going to be your girlfriend or your wife. Respect her feelings and respect yourself, and move on.
If a woman tells you she just wants to be friends, then move on and find a woman who wants you to be more than her friend. By staying with her for 2 years and spending all your time with her and her children, you’re keeping yourself from finding Ms. Right. If you really want a girlfriend who loves you the same way you love her, then get out there and find her, and if she gives you the just friends line, then exit — quickly! Don’t waste your time.