Deal with it or move on!
There are only two ways to experience joy and peace of mind in relationships: We either get what we want or we learn to be happy with what we have. Accept it or move on. The choice is up to us!
If exes have children they're usually going to be in contact for life.
You always have the option to place on your "must have list" for men that they don't already have children.
Each of us gets to (choose our own) friends, lovers, and spouse.
Know yourself, love yourself, trust yourself, and choose wisely!