how to get a pisces ex back?

I was with a pisces for 3 1/2 years. First we got together for a few
weeks, then she freaked out and ran away for a few months, and then
came back... then we had an amazing loving relationship for years and
recently broke up. Just before we broke up, we were talking about
moving in together and we both were scared. I was being distant for a
few weeks because of work and then she just broke it off,
said we wanted different things, she loved me but wanted to work on
herself.

Since then, I've been miserable - so regretful of not nurturing the
relationship for those few weeks, and miss her horribly. I gave her
space and didn't reach out for a few weeks and then asked to talk with
her, and then she seemed really angry and just cut me off saying "it's
over." Thing is, our mutual friends say she's miserable and was much
happier with me and they think she's just freaking out. What can I
do? I'm trying to respect her pisces space, but wonder if I should
put in more effort -- like send flowers and just write how sorry I am,
how I made the biggest mistake of my life by neglecting the
relationship, that I don't expect her to forgive me, but that I'm
deeply sorry.... and then go silent again. Would that help? Or would
it hurt? :-/ Is it better to just hide away?

thanks everyone.... so, would you say write a heartfelt explanation or first flowers and a little note saying "i made the biggest mistake in my life etc"... then give a little time for her to receive and then write a heartfelt explanation?

in response to the below, i think things can change and this time away from her has been a horrible reminder of how important she is to me. i can't lie and say that i wouldn't need to work on myself -- i'd need to ask to go to couples therapy so that we could have better communication because i think we both didn't open up at the end, leading to a blow-out. so, i'm not prepared to tell her that everything's perfect and i'll be flawless, but that i adore her to no end and i'm willing to go to every length to give us the life together that we deserve, with unlimited dreams, adventures, love etc. does this make sense?
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If she takes you back... will things change? will there be improvement in your relationship? if there is, will it last... or eventually go back to your old routine? These are questions she's probably asking herself. Granted, she should have spoken up before breaking things off, but some Pisces are wonderful at holding on to pain and then bolting.