OMG. That is just heartbreaking.
As for another pup...you'll know when it's right. There's no disloyalty EVER in sharing your love. I know when my little Josie died...too soon, at the age of four...I was frantic to find another pup. It was strange, and the only time I've ever felt like that. It was the right thing...and we loved our Phoebe...the pup I found in my desperation...for almost 18 years. I always felt my Josie's spirit was within her, enjoying the rightful span of years that had been taken from her...much too soon.
I'm thinking that little May puppy probably needs a loving Mom exactly like you.