he's bound to feel devastated if 1. you were together that long and 2. it was you that ended it. you feel cos you can see a person you love very much hurting because of a decision you made. but you had to go by gut instinct and what you felt was right and in the long-run you will have spared a lot more pain and hurt on both of your parts. it's a huge change but feeling relieved should reinforced that it was indeed the right thing to do. you should be proud that you were able to make such a decision and stick to it.
They called us a dead generation,
They told us that we wouldn't survive
They left us alone in the maelstrom
As you can see we're all clearly alive.