I think you've made the right decision. Honestly, if you were 100% happy in your current role, you wouldn't have looked at another job, nevermind applying, being interviewed and then accepting the offer. Something was clearly niggling at you to leave (and only you know what that niggle was).
It is true that sometimes it's better sticking with the devil you know but honestly, I think staying in a role for too long can cause you as a person to become a bit stagnant. Everything becomes too comfortable. I think it's important to push yourself out of your comfort zone in order to develop and grow as a person.
And, as a final note, don't ever feel like you've let the team down by leaving. When you strip back the friendships, ultimately they very well may feel let down that you've chosen to leave, but it likely is a result of them being 'annoyed' they'll have to train someone new and they no longer have an 'old faithful' character who gets on with work without much complaining. These are selfish reasons, especially as I guarantee if anyone else got offered a job with more money/less hours/better benefits, etc, they'd be the first to leave, too. Never feel guilty about leaving a department/company.
Of course, leave on good terms, but ultimately you have to make decisions that best suit you. It's your life. You don't want to be old and looking back on your life and realising that you missed out opportunities because you felt loyality to a group of people who (more than likely) also ended up leaving the company for better opportunities in the future, while you accepted your fate.
I also would prepare myself for some shocks when people do find out you're leaving, too. Unfortunately, I experienced the shit end of this not too long ago. I was a well respected member of the team, left for a new role and suddenly particular people, upon hearing I was leaving, barely spoke to me ever again. Told people I was having an interview when I didn't want others to know, no real genuine congratulations when they found out I got it (just my name scribbed off a rota), no card, no goodbye on my last shift, no conversation for my final week. It was if I had betrayed them in the worst possible way for simply wanting to better myself. And these were people who often told me how great my work was a matter of weeks before.
People can really surprise you, but it's exactly why you should always do your absolute best to make the decisions that are right for you and your family over other people you work with. You never know how people will take it.