I was having a similar issue, but not with myself so much as the boyfriend likes to cook and doesn't cook healthy. Drives me crazy sometimes. He used to just bring me a huge plate of food and since I was raised to eat everything on my plate, I was eating way too much. Now, though, I talked with him and he doesn't help my plate any longer. He was trying to be sweet, but just over-doing it. He still doesn't cook so healthy, but he's been incorporating more of my suggestions over time. If he makes something way too bad, I just have a tiny portion and then add some low-cal fruit and/or veggies to fill myself up.
I agree to have a talk with him about what you need and maybe he will be more supportive. Maybe ask him to only get one portion of an unhealthy food and then NOT share it with you. You can get the 100 cal packs and only allow yourself one of those when you want to eat chips/cookies. One thing for certain, you can eat a lot more healthy type foods than chips/cookies. Those things taste good, but don't do anything to fill you up. Something that helps me to fill up so I don't even want anything else (even junk food), is a low-cal frozen strawberry and diet soda (grapefruit, or tangerine or lemon-lime) smoothie.
It's hard to do without support, but you can do it. Take one day at a time, sometimes one minute at a time, and don't beat yourself up when you slip.