How, is it wrong to love an old friend after a 3 year separation?

Okay so 6 years ago I met my dream girl. We bacame the closest friends and 2 years in I realized I had fallen in love with her. We talked about it and she told me that she wanted to stay just friend because she didnt want to lose what we had. I restpected her decision but after a while holding back my feelings and urges broke me down. So I wrote her a letter explaining how I felt, why I felt that way, and why I had to leave. And I did. 2 weeks later I met someone. The one I loved called me right after and like an idiot the first thing I said was I had met someone because I thought she would be happy for me since all she wanted was to be friends. Well… I got hung up on. So 3 years lated my girlfriend and I broke up. That was 7 months ago now. And last week my dream girl contacted me. So we met for lunch to catch up and she now has a one and a half year old doughter but no dad. And a boyfriend of a month who is in the millitary, has money, and is good with kids. She told me that when she called back then she wanted to tell me she couldnt lose me and she was ready to take it to the next level. She told me that she still has my letter and never stopped thinking about how or where I was. And she told me that she I dont have to run away again. Well I expressed how scared I was that I would fall for her again. And I couldnt go through that again. She told me to let her know if get stronger feelings for her, but didnt tell me what would happen. I cant leave her again. And her doughter thinks im her daddy after meeting her once. Which is great, cause I know she likes me. But it is just a matter of time before I fall back in love. It feels like because she knows it will happen but told me I cant leave her again that she is waiting for me to tell her I love her again. But I dont know if I should just tell her when it happens. Or what? What do I do?