Unless your book is a blatant plagiarism of that earlier book (which from what you're saying it isn't) you have nothing to worry about. Lots of books...
Personally, I would keep sending out queries until I had a firm offer, as it could turn into an R&R that you may or may not want to take them up on....
My R&R with a publisher turned into a rejection and, to be honest, by that point I was glad to close it out and then I got a better deal anyway. I'd...
Ditto all the wisdom above. Also, shout-out from mom-dom and writing-dom and trying-to-do-too-much-dom. Definitely be gentle with yourself and don't...