Welcome to our forum.
I see what you mean by thin ice; it sounds like your partner is hesitant about each little step forward. I am guessing you will have to take things slowly, even though you may be yearning to put the gas pedal on this new relationship (with your ex-girlfriend). In poly, we usually try to go at the pace of the slowest person (as long as it's not a complete standstill).
If you put a link in this thread leading to your next thread, I'll follow it and try to help out.
Glad to have you aboard.
Love means never having to say, "Put down that meat cleaver!"