Heart health on a low income

I am a 27 yr old female weighing in at 166lbs at 5foot 4inches tall. I am definately not at my ideal weight, and my doctor just informed me I have extremely high Triglyceride levels. She has put me on medication and has told me I must change my eating habits and lose about 30lbs. I am finding this very difficult with my current financial situation. My partner just lost her job and Im having to support the household on my own. "Diet" food is rather expensive and I just dont have the luxury of buying myself "special" food when I have to feed my family on my limited income. I am very frustrated and worried because its not just a vanity issue, its a health issue. What do you do when unavoidable life situations keep you from living a healthy lifestyle? My doctor has given me 6 months to get my cholesterol down and I just dont think I can do it.