Victim focused investigations is something Hampshire are really quite hot on now. When we attend a job, we need to agree with a victim, how often they'll be updated (even if the update is that we're still waiting for something else), by what means we'll update them and a load of other bits and bobs. If we don't make a log of this contact or attempted contact (such as leaving a voicemail) then we get chased by our sgt when they review it.
At the end of the day, if you're not kept up to date with what is happening then it's perfectly reasonable to feel like you do. More and more forces are recognising this and putting processes in place to make sure victims are at the centre of all investigations.
There is a point when the CPS are given a file to make a charging decision, and there's not much the police can do until this is finalised, but they should then tell you what the decision was and what rationale the CPS had for making that decision. You won't always get the result you want but at least you should have some rationale for why it didn't go to trial.
By the sounds of it, your case was serious (the fact a DI was your contact hints at this), the suspect did get charged and you then had issues at court. Clearly the Police should have been more engaging with you (and hopefully this will be the norm in the not too distant future) but like I said, sometimes the Police feel failed by the CPS although I'm sure they have their own set of frutstations.
