Body image.

You can raise your self esteem for a start. You have/are raising five children? That is something to be very proud of.
I'm not surprised you weren't happy about child number five (you don't say how old this child is).
Your husband decided you should have another child you didn't want? You need to take ownership of your own reproduction!
I would love to be 75ks too-you don't say your height but to me that isn't overweight.
You don't have a body image problem-I think it is way much deeper than that.
I would start by getting some counselling and see if you can raise enough confidence to take more control over your life. Good luck and start appreciating your own worth.