Am I the one that does not get it?

Last night mu sister and I were setting a goal to see who can make it to their desired size before May 1, 2010. We were discussing our bet to see what would motivate us the best. We mentioned a trip to Vegas, hotel and all that the loser would have to pay, just then my live in boyfriend said to my sister "that's not fair because you know you are going to win". I was like what kind of support was that, then I said "that was not nice, this will motivate me because I can't afford that and I would love to have it"....just then my sister trying to make me feel better said "you could do it, you are ready look like your losing some weight"....just then he very rudely said "hey don't lie to her like that, she looks the same".....I was ready to cry with tears at the tip of my eyes but held it back and just let it go. Then my sister told him not to be mad that this was just to motivate us, if we both met our goal, then non of us have to pay.....then big mouth said "I am not mad just don't bet something like that because she can't afford it". I was just so hurt and speechless. My mom and sister left and I was just quiet then went to bed. he tried talking to me last night but I just did not want to, so this morning he asked me why I was hurt, so I told him and his answer to me was "I am not going to allow your sister to lie to you and say you are losing weight when you look the same", then I told him "how can you say it like that, so cold, I know you don't understand when sometimes we need a little white lie to motivate us especially when I have been depressed for so long". I did not expect him to understand but did not expect to hear what he said after. He said "Here I am trying to avoid what happened when you had the baby (she's 2 now) that people where telling you that you were losing weight a month after having her and look at you now with those lies". I told him that I have been so depressed and that post par-tum hit me really bad and you did not help me get over it with all your rude and hurtful comments all this time, about everything. His answer was "Like I mentioned before, is this the way I will have to live all my f___ing life not being able to say anything because it offends you.....what kind of life is that for me". I finished making breakfast and left to my room and posted this question......Please help am I over exaggerating and just making my self feel sad? Please help!!!!!!