Replaying every aspect of your relationship wondering if you did something wrong and if it was your fault.
Not having anyone to share anything with.
Loneliness and lack of intimacy.
Having to work like a dog all day and then come home to more work and trying to fit in quality time with your child.
having your ex dump you with all his debts and having to spend the next four years trying to sue him for the money back while you scrimp and save trying to pay all the monthly payments as he buys a new house, a new car and goes on foreign holidays.
Having your ex refuse to pay child support and then tell you that if you need the maintenance money you obviously cannot manage so should 'give' your son to him and he will give him a better life and you can just visit!
Putting up with the fact that your ex does not speak to your ds or have any other contact with him outside of the two night visits he has with him once a fortnight and then have him spend the time telling him how much better off he would be if he lived with daddy.
Having your ex - who left you for another woman and now has another child with her - tell your son that mummy shouldn't have a boyfriend because she is selfish and should be happy just loving her son!
Hearing your son tell you that daddy said he doesn't like you... whatever happened to respect and common courtesy.
I could go on but it would just be ranting without purpose!