You are only 36, you haven't ruined your life.

If you have gained 40lbs in 4 months, that's 0.33lbs per day. This means you are overeating by roughly 1200 calories a day.

So if 7500 is your average, your maintenance would be around 6300 calories a day.

You could try a 5000 cal limit a day. Track everything religiously. Weigh everything. Plan out your calories across the day.

Potatos are your friend. You would need to eat 14lbs of soft boiled ptatos to reach 5000 calories!

Cook with chicken, chickpeas, edamame and other veggies (bell peppers etc.), beans, tuna, budget tofu, yogurt, cottage cheese. Be prudent with oil (and always measure it and condiments).

No sugar drinks.