I have tried:
---Blaming other people: "They did this to me."
---Resenting other people: "He/she doesn't know what it's like to be fat."
---Asking other people to change their habits to benefit me: "Please do not eat Those Things in front of me."
---Asking other people to keep me accountable: "Make sure I don't eat Those Things."
Not only does this totally not work, but it also creates animosity between you and those you tried to use as a crutch. Instead of making yourself accountable, you blame your failure on other people and separate yourself from the issue.
Now, don't get me wrong here: Should people, especially loved ones, support you in your goals? Yes. Do they always? No, and that's ok. You're doing this for yourself, not for them. This might mean you will have to create some distance between yourself and some people, especially if you can see that they are deliberately sabotaging you. (No, really... people do that.)
My husband is a wonderful man. Do you remember those "Things I've Tried" up there? I've done all of those to him, the poor guy. It was a hard pill to swallow to realize that he was not the one making me fat. Now we have our little after-dinner, after-kiddos-in-bed snacks: he has whatever he wants (delicious nutty buddies included) and I usually have a little popcorn or an orange. It is delectably satisfying to slap cravings in the face, enjoy a delicious HEALTHY treat, and own up to my own responsibilities. I made myself fat, I will make myself thin.