Welcome to our forum.
It sounds like you've been through some scary and glorious months lately. I'm glad that D has been so understanding and accepting about your relationship with E. Things will probably be a little rocky in the early years, but you'll gradually get your dynamics figured out and the road will become smooth.
Hopefully Polyamory.com will be a valuable source of information and feedback for you. Check out our various threads, and post any thoughts and questions you may have. There's a lot to learn about the do's and don'ts, etc.
Glad you could join us.
Love means never having to say, "Put down that meat cleaver!"