Remember that when you are old and on your death bed the one thing you will NEVER regret is "I didn't work enough." NOBODY regrets not working more at their job because it's not the most important thing in life.
When you are home you are HOME- that's it. I always tell myself stuff can WAIT till tomorrow- if you do it or not it'll still be there the next day AND besides that there will always be more work to do when it's done. You don't want to work so hard that you get yourself stuck in your position because they won't want to promote you so you can get that work done.
You say you have gained 30 lbs- well why not use the time after work to "work" on yourself. Join a gym and go straight there after work, get your work out on, then go home and shower and relax and do anything that is NOT work related.
I used to take my work home, practically kill myself for the places I worked. And yet when the time came for lay-offs the company didn't even BLINK when they let me go. It was very devastating for me but it made me realize I'm killing myself for no reason. At the end of the day my current job gets me from 6:30 am to 3:30 pm and that's IT. I spend that time at home on me, my husband, my family, and my pets.
I agree to find something you love and go for it. Your health is a good start, if you like to cook start cooking more. If you like to read join a book club, etc.