I was with my last ex for over 6 years and she was very much my best friend as well as my partner.
It's been somewhat over a year now since we broke up and I do still think about her and miss the friendship, chemistry, etc. etc. as well as often wondering "does she still think about me?". To be honest, wondering whether they still think of you is probably the hardest part. We shared a lot of interests so a lot of things 'jog my memory', as well as certain things that I see/hear/do occasionally that just makes me think she would have liked.
I would never get back with her, though that's due to the specific circumstances as I simply couldn't trust her again + I burned that bridge to make sure I never do so and we have had no contact since. Like you though, I still care for her and if I happened to see her around and she was 'in trouble, or hear she was 'having a bad time' I would likely still go out of my way to help.
I can't say how to get over your 'first love' since despite the amount of other girls I've been with, she was the first and to an extent I'm still in the process of it (6/7 years is a lot to get over). It gets easier with time though, you find ways to fill the voids and it gets easier. Having those memories is nice because they still make me happy at the same time.
To be honest, I've gotten to the point now where it doesn't really make me sad anymore, they're just happy memories of something that 'used to be' like a lot of other things in the past that I can look back at and smile.
'Getting over it' (like other things) isn't the same process for everybody though with everybody doing it in their own way, and it's never guaranteed how long it's going to take somebody to do so.
Thank you very much for sharing your insight and personal experience. It helped me quite a bit as I am experiencing similar things in regards to my own breakup. I'm glad that you are able to look back happily at this point, though. Sometimes I am able to do that also, but at times it does get hard. Thanks again, though.