I need help and advice PLEASE!!

Laura • Married to my best friend and I am blessed to be able to be a stay at home Wifey and Mommy to 3 beautiful kids!
My Husband and I have been together almost 10 years we have 3 beautiful children Ryan 16 Madison 11 (both my step children but we don't use the term "step" at our house) and James who is 9 but has been raised by my husband since he was 1. Our other 2 children live with there mother who is a complete dead beat and only wants the kids for child support. They obviously had a horrible relationship she got pregnant 2 while my husband was deployed etc.. You get the picture anyway while he was with her my husband had a vasectomy because he never thought he would marry again my husband is 38 I just turned 29.. I want to have another child so badly and tonight my Husband finally admitted he would not get a reversal done because he said he couldn't take it if we ever split up and go through the custody battle with me. I of course assured him I would never take away the child or split up with him for that matter. But he won't budge! I'm still young and it's all I think about has anyone been here or have ANY ADVICE? Thank you in advance 💟👼🏼