I'm so sorry for your loss... and I know how you feel.
In 2000, when I was a sophomore in college, we lost our beloved family pet, a Sheltie named Specs. Even now sometimes when I talk about her or think about her, I get choked up. But, like others have said, getting a new Sheltie has really helped me immensely. As previously mentioned, the new pup doesn't replace your beloved companion... but it does give you something else to focus on, as well as lots of love and comfort.
And speaking solely for myself, it also provided an outlet for all the belly rubs and head scratches that had been building up in my system for all those years I was without a Sheltie. And, there are times when Lerwick (the new puppy) will do something-- move in a certain way... look at me a certain way... lick the silverware in the dishwasher as I'm loading dirty dishes--that are identical to the things Specs used to do. And for those brief moments, Specs lives on again.
I hope you can find peace, and are able to look back and smile at the memories of your precious Sheltieboy, and yes, when the time is right, to add a new companion to take up the mantle and walk bravely by your side as you journey through life.