Way to go on the already ten pounds lost! Sounds like you're off to a great start and taking this seriously. Love your username by the way
I think making big goals are fine as long as you aren't too harsh on yourself, and willing to make compromises. Like, if you don't loose the desired 75 pounds, BUT you never went off plan for more than a day or two at a time (I.e. not giving up at a plateau or for months on end) I'd say still treat yourself, especially since the whole family benefits from a vacation
I think you have to carefully balance what your self esteem can handle and what it can't, what's rewarding and motivating versus whats belittling and punishing.
Let us know what your plan is, I love hearing what others are doing! No two bodies, or plans, are ever the same.