AITAH for dating my friend’s sister after I told him I wouldn’t?

I (21M) met my friend “Jake” (21M) in January and we got really close very quickly. About a week ago I met his sister (20F) and we instantly hit it off. Things moved fast and we’re now thinking about dating. We’re both really happy together and the chemistry is great.

Early on when Jake and I first became friends, he mentioned he doesn’t like his friends dating his sister. I told him I wouldn’t do that. At the time I genuinely meant it, but when I actually met her the connection was immediate and strong, so I went for it.

Jake is now absolutely furious. He’s raging, saying I betrayed him and that I’m a terrible friend for breaking my word. Our friendship is basically over.

His sister and I are both adults and we’re happy, but I do feel bad for going back on what I said. At the same time, I don’t think I should have to throw away a good relationship because of something I said months ago before I even knew her.

AITA?