I have that husband, too. He met me when I was around 275-ish and 40, and chased my tail every day since. I made it up to 323 and he never acted like I was anything less that a freaking supermodel. He's never said anything about my weight except "I think you're perfect the way you are, but if YOU want to lose weight, I'll help you in any way that I can." And he does. When I went on my pre-band diet for a week, he went on it with me - because "it's hard to do alone". He's still on a very low-carb diet with me now, because he wants to support me and go through what I'm going through. And because he feels that he could stand to lose weight anyway - why not try to keep up with my wife? Lol.
I would tell a man I was dating eventually - but no, not right off the bat. I'd tell him because in a real relationship, you want to know everything about each other - and this is a big part of your life and what you've gone through. If he really likes you, he'll be like, "Oh,... cool. Good for you!" It's amazing to me how little men care about how you go to be who you are today. If they like you now, they're thankful for anything that got you to be this person. They couldn't care less about what you do for a job, or why you have that scar there. If they like you, they like you.
I hope that you can see yourself as someone who attacked a problem when you didn't like something about yourself. You didn't just get surgery to fix it; you got surgery and then did the necessary work to take the weight off. The food you're eating now is different in quantity and type than what you were eating before - YOU did the work. You were willing to do the work so much so that you took drastic measures to make sure the issue was solved. And as a result of your tenacity and hard work, you're healthier and likely more beautiful (inside and out). You are to be applauded, and I bet he'll agree. If he doesn't, then he's not the right man for you.