advice. I need to stop breastfeeding

I need helpful advice. I've been suffering from postpartum depression since my son was born. I've been breastfeeding him because it's good for him and was said to help us bond and my depression go down. 
I'm at 18 months of breastfeeding and my mental health is suffering more now and he will not wean. I hate breast feeding. I don't want my boobs touched. I want my body back. But my son won't wean. I just want to stop breast feeding. I'm tired. He eats well on his own but still demands and pulls at my boobs. 
I just want to cut my boobs off and cry in a closet. Can someone please help me with advice on how to get him off the boob. I'm struggling so hard. I hate myself.