It sounds like you already know how to lose weight. The question is how to not lose so much muscle. You need to eat protein with every meal and it's better if your snacks are a quality protein too. IE a handful of nuts, a hardboiled egg, some peanut butter, or I make sugar free baked treats with chocolate protein powder (no flour-see youtube), sf jello with protein powder as my snack before bed if I need one. There's lots of ways to incorporate more protein into your diet.
Also, try adding more weight bearing moves to your routine. Squats, pushups, planks don't require equipment. Weight bearing moves should follow your cardio routine. I usually do and hour of cardio followed by 1/2 resistance training. The less fat you have on your body the more your muscles will pop too, you'll see more immediate reward for your hard work. Muscle burns more calories at a resting rate so your metabolism will speed up far more than when you're only doing cardio. All the best, keep up the good work!