Fiance says I'm getting too thin, get more muscle (really?!)

Congrats on what you have already achieved! Stick to what makes you feel good. Maybe talk to a personal trainer at your gym who can give you some tips and advice with the weights ut dont completely change everything up. Good luck and let me know if you want me to share some p90x work outs with u

First off, let me start by saying “Congratulations!” for the weight you have lost. It is a significant accomplishment and you should be very proud of yourself. I’m personally not too familiar with the insanity workouts, but I do know that you may have more gains with P90X. Please note that I don’t think either of these workouts are designed for you to bulk up. Both are more geared toward athleticism, lean muscle mass, and a “cut” appearance. I would suggest that if you’d like to lose fat as well as increase muscle gains, then you should focus on getting enough protein & whole grains into your diet as well as cut back on cardio. I know you say that you have more fat to lose, but if you did P90X, you would lose that easily since your metabolism would skyrocket- you will gain muscle(but you shouldn’t bulk up to be huge). One of best way to lose fat is by increasing lean muscle mass. If you are overdoing cardio, especially for long periods of time, there is a possibility that you could be breaking down muscle mass, but it is probably most likely due to lack of energy stores(calories). You can also try to take some amino acids to help your mucsle recovery L-Citturline, L-Orthinine and L-Agrinine- reasearch them if you get time. Here is an article I found that may be helpful. Good luck!
“Losing muscle has more to do with inadequate diet than with excessive aerobics. If you suspect you are losing muscle there are four likely causes:
1. You are not eating enough protein. Protein is the only nutrient that is actually used to build muscle. To stay anabolic you must eat five to six protein containing meals. Each meal should be spaced out approximately three hours apart. Research has proven that if you are physically active, you need a minimum of .8 grams to 1 gram of protein per pound of bodyweight.
2. Your carbohydrates are too low. Low carb diets are often used for fat loss, but it is a mistake to cut your carbs too drastically. Carbohydrates are protein-sparing , so even if you are eating large amounts of protein, you can still lose muscle if you your carbs are too low.
3. You are not eating enough calories to support muscle growth. This is the most common cause of muscle loss. When your calories are too low, your body goes into "starvation mode." Your metabolism slows down and your body actually burns muscle tissue to conserve energy. Muscle is metabolically active tissue, requiring a great deal of caloric energy just to maintain it. That's why your body will shed muscle if it thinks you are starving.
4. You are not training with weights. It is a common misconception that if you want to lose weight, you should start with cardio only and add the weights later - another big mistake! It is the weight training that keeps you from losing muscle while you are dieting.”