I was only thinking the other day, no man should be a father until they're 30 - they're generally just so immature in comparison to women.
Tell him if he can't say anything nice then to not say anything at all. Most men need that tatooing on their foreheads!
Good heavens you have just accomplished the most miraculous thing, creating a new life! And he's whinging about some baby weight gain!
For yourself, I think you need to get a very strict handle on your thoughts indeed. Try to catch yourself thinking negatively, then stand back and objectively ask yourself is that thought true? Do you really agree with it? Then tell yourself something positive about you to replace the negative thought and repeat it regularly. Get in the habit of looking at yourself in the mirror every time you go to the loo and seeing something there to admire and feel positive about - your eyes, your hair, your smile. Take charge of your own thinking and shut these stupid, immature comments of your partner right out.
I think when your thoughts go round and round that is a sign of stress, which isn't surprising as you've just had your first baby and you are not getting much support. And no doubt you are knackered. So try to get as much rest as you can and make sure you do something (however small) for yourself every day. Be kind to yourself and think positive about yourself and you'll soon pull out of this.
Congratulations on your DD and take care x