I always struggled with a healthy weight and had to hear hurtful comments from family about and after my pregnancies--even though I was within a healthy weight range, just higher end, and only gained 30 pounds with each baby. Some people really do not see beyong size and struggle to look at someone and not assess what they want to see different. They need to learn to keep their mouths shut about it. It is okay to have an issue you are not allowed to talk about--it might be how you choose to discipline your children, what church you go to, the fact that you do not force your children to eat five pieces of brocolli at the table, or, in this case, your weight. If you state very clearly that any and all weight related conversations, unless you ask them for the opinion or information, must stop. If they bring it up, you will remind them politely that that is something you do not talk about. Change the subject or end the conversation, leave, etc. It sounds harsh, but I had to to do that with the "subject" of my husband. My family can't say nice things, I am not going to listen to stuff that ludicrous; if they want to talk to me it will be about something else. If your weight is ballooning way out of control and you are suddenly at risk for a million conditions, your husband should be the one to talk lovingly and supportively to you about it. If you are unhappy with your weight and appearance, that is a talk for trusted girlfriends or, again, your husband. Unless you are confiding your frustrations with your family, they should not be talking about it. I am thankful that I have never had a "skinny" friend who made me feel bad about the way I look, but they have always been supportive whatever my health goals, whether I achieve them or not.
Comments will always hurt, even if they are kind or oblivious. People will always make them, but you might consider making it an "off limits" subject. I know how hard it is to be firm with family and still struggle to have comfortable communication with them since I got married. Have a wonderful Mother's Day tomorrow, and that is seriously great for you that you can shower and wear makeup--I'm lucky to shower every other day and only wear makeup if I'm in a meeting (sometimes)! :)
P.S. If they think at 5'7" you should be at 130 pounds, they are insane! I am a little shorter than that and cannot imagine being healthy at that weight--I know some women are, but a huge range is healthy for your height.