Masturbating to a close family friend, is it normal?

One night a while back, I had been home alone, and decided to masturbate in my room. I usually make up my own little shows in my head, but this one was different than the norm. Growing up, one of my mother's best friends was like a second mother too me; she has known me ever since I was born. But when I was masturbating, I couldn't get the idea of her having sex with me out of my head, and this was also the first time that I have ever thought of her in that way. As hard as I tried, the image wouldn't go away, so an hour later I eventually decided to welcome it, I mean it's not like it's gonna harm me or her right? So I kept going, and going, and going. And when the time came and I was ready to burst, I pictured me cumming inside of her, both of us moaning in ecstasy. When I climaxed, it was the most powerful orgasm I'd ever had; I unloaded so much that I actually covered my stomach, waist, hands, face, hair, pillow, chest, and shoulders (As I said, the most powerful orgasm ever. I'm being totally honest.). I came so much that I was actually sore for two days. I was more than content when it happened, and I actually took a moment to bask in the afterglow of it. But lately, I've been feeling conflicted about the whole ordeal; as I said, she's been a close friend of the family for years and watched me grow up, basically like a second mother to me. Is this normal or ok? Was it weird for me to do that? I mean it's not like I have ever imagined her like that before; I love her, in a son or nephew kind of way, she's like another one of the family. And no, I don't want to have sex with her, it was just a one time thing, so don't suggest that I make a move at her.