I think my husband thinks I'm at work but I'm spending the day at the gym alone with my computer treadmill and healthy food.
Is there a reason why you are spending all your free time at the gym?
Because I don't want to spend time with my husband; we don't get along that well
It is normal for couples to have separate hobbies but when you are using that hobby to get away from your spouse it is bad. You shouldn't be deceiving him like that, he would be very hurt and it could damage your marriage.
I don't care since we are just staying together for the apartment.
Are they aware of that reason? I think that you should be honest to them. It is just going to hurt you both worse in the end if you are deceiving the people that care about you the most.