I am sorry to read family members are already suffering the consequences of diabetes.
When they say, diabetes is genetic, they refer to how you store the fat, in your middle section on your organs or your butt far from your organs, not that it is inevitable that you will get diabetes too, or some eating patterns that are often shared in families.
You are already trying, by eating healthy - but maybe a bit too much of it - and moving. You already have the mindset, you just need to tweak your diet a bit.
Anything that has "sugar" in any form or shape written on a label, you do not eat. It doesn't matter if it is agave, honey, rice syrup, .natural, organic, pure, brown, maple syrup ... Sugar is bad. Then come the fast carbohydrates, which are the pasta, rice, bread, most cereal, and the very sugary fruits.
However do not cut ALL carbohydrates. You must keep the slow carbohydrates such as the chickpeas, lentils, beans, even carrots and pears. In other words, those that are whole and in their natural form. It is important to keep the insulin production because going too low carb might actually make insulin resistance worse, in a you snooze you lose (a function) kind of way.
Keep steamed and raw vegetables ready in your fridge. A whole cauliflower, green beans, sliced bell peppers, ... Have a container with quinoa. Have some seeds in the morning with yoghurt. Not too many, same with nuts, just a few as they are very calorific.
Keep your workouts. Abandon takeaways. Eliminate ultra-processed foods. Ditch everything that doesn't fit the optimal diet. Gift it to food bank if unopened. You don't need to keep anything in the house. Not for the kids/grandkids, not for your DH, they want something sweet or fried, they have it outside the house.
You and your health come first.
Use this thread for motivation and accountability. Report back from time to time, and we will keep you going.