I have been in your position many times with boyfriends having way too much of an opinion about what I should be doing with my own body. Make your goals easily achievable, for example, tell yourself that you're going to track your food for a week and stay within your calorie budget and then once you've done that for a week, tell yourself you're going to do it for another week. 70 pounds can seem daunting when you look at it all at once.
Best of luck on here! If you want to add me as a sparkfriend so we can check in with each other, I'd be more than willing to offer you some support!