How to tell a woman you're falling in love with her?

OK, I recently been seeing my ex's best relationship just hanging out, dinner, drinks, talking til the sun comes up and amazing sex. At first it was cool, but lately I been having real strong feelings for her.How do I go about telling her this without scaring her off? I'm a grown man and I know when it's love and I'm man enough to admit I'm falling in love with this girl...but I'm scared to say anything because I don't want to ruin what we have going on now.

She hints that she has feelings for me but never really comes out with it, I get texts from her saying stuff like "you make me happy" or " I've never been this happy before, not even in the 6 years I was married" and "miss you" etc.

Ladies does it scare you off when a man admits he's falling for you? especially if you guys aren't in a committed relationship?

Like I said I don't want to ruin anything but I can't keep it inside either.Every time I'm around her (which is damn near 24/7) I want to say something but don't. How do I tell her? or do I wait for her to hopefully one day come out with her feelings?

By the way my ex doesn't know about me and her friend, kind of keeping it on the down low.