Methinks, you've answered your question already.
What you need to know is that contacts are and the exel spreadsheets are just that, all useless without someone who is pa**ionate behind them.
What's working is not the contacts or excel sheets: it's you.
So forget about everything you have come up with for them it's petty, plus it's good for your track-record and you're proud of it, right?
The only thing you should keep is a pa**ion project or strategy that they never supported.
Even then tell them you are going to use it.
When they stop you, remember, if you came up with it, you can come up with more and bettter...
Finally, concerntrate on the new (positive) gig and not showing (negative) them how much they need you!
You resigned because you don't take shit from anyone and not just to spite them.
Big difference!