Diet: How do I keep it from happening?????

Jon is tormenting me!  I did so well yesterday until dinner.  I had a TERRIBLE day at work.  Sunday I had to go in for a couple of hours to participate in a phone-a-thon, which sucked, and yesterday was devoted to writing letters (of course, a project I had to do myself), mail merges, stuffing envelopes...  And my boss was bugging me about shit ALL DAY.  Finally, I was like, "Do you want this to get out today?  Because if you do, I have got to concentrate on this, and what you're asking me to do right now isn't going to happen until tomorrow."  That still didn't work.

So, I got home last night with a raging headache.  I started some laundry and fell asleep on the couch.  When he got here last night, he was like, "Yeah!  Thai food!"  I'm a sucker for Thai, I was cranky and didn't feel like cooking, and I just simply don't have enough food in the house to feed him - he's big (like, 6'6).

I don't want my diet to effect Jon, and I know he needs to eat a lot more than I do.  I really don't want to cook for him because a.) he can't eat what I eat as far as portion size goes, and b.) I can't afford to feed him.  What do I do?  Just tell him he's got to fend for himself for dinner?  

In the evenings, I feel like I just have to satiate him and entertain him and I can't do anything for myself.  I have to field his well-intentioned questions about my day, even though I'd rather not talk about it (I've told him I don't like talking about work because it pisses me off... and it should piss him off too, because every time he drops by my office when his store is closed or he decides that it's just not worth him being there, they put him to work packing or delivering Matzo or something...).  I have to eat with him, and he's always like, "Burgers and pasta and sushi, oh my!"  And then there's the nightly MSNBC routine - Keith Olbermann and Rachel Maddow - which eats up two hours of my time.  Then there's the sex, which if I don't give him at least a couple of times a week, he gets pissy (not like it's necessarily a chore to have sex with him, but that eats up an additional hour of my night).  By the time 11:00 rolls around and he's ready to go home, I feel like I've devoted my entire evening to him, and haven't done ANYTHING for myself, and oh god, I have to go to bed now so I can get up and go to work in the morning and do the same bullshit all over again.  

How do you cram boyfriend time and exercise and separate meals into your routine?  Most importantly, how do you manage to keep your diet going when the people closest to you aren't dieting?  I have a really hard time with limits and goals and keeping myself on track, so I'm really asking for advice.  What am I going to do when Jon and I eventually live together??