Hi - I'm really sorry to read your post.
I too have been in this exact situation, 8 years ago now though.
Maybe a break is what you need? Do you have someone else who can support you or maybe DH would take the baby for a couple of hours so you can have some 'me' time every now and again?
When my XH went I was obviously upset but when that had passed it felt like a breath of fresh air. AD's made me feel detached, I don't think they were for me.
Believe me, I went to hell and back but slowly things got better.
I never got back with H, but we are good friends now.
Let yourself feel sad, cry your tears, then tell yourself how brilliant and strong you are and how lovely your LO is and do some things you enjoy. A walk in the park pointing out the sights to your son could work wonders!
I know it's hard, I really do, have a virtual hug and whenever you need support just come and talk to all the wonderful people here.