Congratulations, Healing&Hopeful !
It seems that the sun is shining brightly.
I am not sure you even need to speak with your current boss. It seems to
me that your potentially future new boss will just speak with you (he even asked
you to not speak directly with your current boss... So...) in the coming days, so
why worry about your current boss is thinking, etc... Just wait for the offer

.
In terms of negotiations, etc... A few things that I heard or read and that have helped me...
- 'Oh you still have scruples about doing a job. When you have, other people
less competent with less scruples will do the job at your place.';
- 'Do not worry about being good enough. We all do. The only fact that you reached
this point and that people think that you are good enough means that you are good
enough.';
- 'I asked for a good salary. If deserve it. If I take care of myself, it is a sign that I
will take good care of the company.'.
I might even recommend you to not worry about salary. This should come up in the
discussion from your new boss. He he

... I cannot stop smiling... This sounds all good.
So... Relax... You are good, they want you...
Don't get pulled back into the web of your old boss. Stay nice (polite) with her. Nothing
more. (You can use the tricks like 'Oh, could we speak of this next week?')
Enjoy

...
SurviveAndGrow.