Heart controlling what the mind does not want

I am in a relationship with a woman who is 10 years older than I (I'll call her Lynn), and she has a daughter who is 10 years younger than I (I'll call her daughter Kathy). When we first met, I saw her daughter as just that, her daughter and nothing more. Over the years, I have come to realize growing feelings of affection for her daugther. Lynn and I seem to have nothing in common whatsoever, and cannot communicate at all. Kathy is aware that I have feelings for her (she can tell on her own, I didn't tell her), and although she resides here in the same house with us, she seems to stay as far from me as possible. Civil to me, but distant. I have tried everything possible to convince myself that this cant' happen, shouldn't happen, and is nothing but trouble. But no matter how much I tell myself "NO!" my heart just wont hear it. My feelings for Kathy aren't ones of lust, but of what I believe are the REAL thing. I've been married and divorced, and been in at least half a dozen serious, committed relationships before this one. I've read all the books on morality, self-help, and have a strong religious faith. I am a mature adult, who is college educated. I've never wanted children ever in my life unless I'm thinking of Kathy. She is the only woman I believe in my heart that I can love to full capacity until the day I die, never swaying, never questioning, and always honoring her as my wife, should the future deal that to me. My question is this: Should I end the relationship with Lynn and get as far away from them both as I can get? or should I make my hearts feelings known and pursue what my heart wants? FYI: Lynn is handicapped and she and her daughter have few places to go. Option #3: Keep my feelings to myself and let Karma dictate what happens.