I was EXACTLY the same with DS. It took me 4.5 months to even leave DS alone at home with DP while I went 2 min up the road for a haircut. Even then I didnt let them shampoo because I thought it would take too long. Dont get me started on the mini heart attacks I had everytime someone (including my parents who I am close with) held him.

For me it was babysteps, it was finding the boundary between my style parenting and something that was healthy for DS. It was healthy for him to be held by his grandparents, to spend time with his dad without mummy overlooking.
I started by increasing the time I left DS home with DP (having said that, Ive still only worked up to 2-4hrs at most and I spend that whole time checking my phone),I started letting my parents have time playing with DS while I was home, then after a while increased that to them watching him while DP and I went out to get some quick shopping,increased again to them watching while DP and I went out to movie. The first time we did that DS was 10months, and I cried the whole way there. I dont get as upset anymore but I still check my phone the whole time

HTH - good luck finding your path forward.