This is the textbook reaction, Lara, to no-contact. So many here can testify to it. We take the groundbreaking action of breaking a toxic pattern with the addict, then after a few days, we ask "What did I do? What have I done?" And we want him back, under any circumstances. We want to write to him and tell him how much we love him and how important and beautiful he is. We start watching our phone, our mail, hoping he will be in such agony that he will violate the no-contact boundary and call us full of misery and begging us not to go away forever. The minutes and hours of our days become thick with obsessive thoughts about him. And we just CAN'T BELIEVE he hasn't called even though we told him not to.
This is the script, Lara.
You can go one of two ways: you can write the letter you want to write and prove to him he can't believe a word you ever say about what your intentions and boundaries are. Inflating his addict ego to even greater proportions. (Don't let his false humility fool you).
Or you can continue to break that toxic pattern of dependency and control.
We know how painful this is. But in recovery it is suggested again and again and again: take the long view.
Do not be like the addict. Let go instant gratification. Get out of the way of your Higher Power and your addict's recovery and his Higher Power. Do what you are doing: concentrate on your own therapy and being a present mother to your small son. For 85 more days.