OMG I was just coming here to post on my thread about the exact same thing. I think I could have written your post nearly word for word and I'm soooo sorry! I just don't have the words myself since Im going through the same thing.
I just lost my golden boy a week and a half ago (also 1 month prior to his 13year old birthday) from DM as well and just this morning I had to put down my golden girl (14 1/2) due to old age. She had just severely deteriorated over the last few days and I had to let her go so she wouldn't suffer any longer. I totally get where you are coming from and being heartbroken. I wish I could tell you it gets easier but its still too early for me as well and at this point Im still not exactly sure how Im getting through each day. I feel like I'm on auto pilot and my life has just been turned upside down.
I can only hope for the both of us that it does get easier and you can find some sort of peace that at least they are not/ will not be miserable any longer and are able to run free again without any aches, pains or difficulty getting around at the rainbow bridge. Even though it was hard to understand at first, particularly the first few days I now do believe they are with us and I believe I have received "gifts" from my boy recently. Please do at least know that there are others right here with you and hope you don't feel so alone. Feel free to PM me if you need someone to talk to that is grieving right along with you.
Huge virtual hugs to you and your babies!