Bullying

As a child and teenager, I was never bullied. Lucky me.
I now work somewhere where I have never seen any hint of bullying in seven years.
Today I had a text message that nearly floored me. It's not the first time. It was from the idiot I divorced. Sharing our dog was never going to be easy and I knew he would attempt to wear me down in order that I gave up. I didn't expect quite so much quite so soon.
I burst into tears at my place of work today, and for the second time this week. I cannot describe to anyone how this person makes me feel. I wish I could get people to feel what I feel, just for a second. I cannot be strong like they want me to be. It's not there. I am all out of strong where he is concerned.
Going in for teabreak this afternoon and to hide my tears from people I work with, it dawned on me that this is what bullying must feel like.
I cannot cope with ANYTHING. I shake. I make no sense to anyone which they find understandably frustrating. My first reaction is to phone the people who love me. I feel like I need rescuing, and someone else to deal with it. I feel guilty that there are other people dealing with much bigger things than this, but after this length of time, my reserves are so low. There is no fight left.
Some people I work with are amazed at how calm I have remained - and by this they mean I have not swung for him or had someone else do it. This is not me. I cry. I run to my mum. I run to my family and friends.
I wish I could find some way that it would all be water off a duck's back. I don't know how to and I feel pathetic. I am well aware that a professional woman in her early 30's should not become a gibbering wreck at a few spiteful, bullying text messages but that is in fact the reality.
There is no reasoning with my ex. He is the most unreasonable person I have EVER met. He denied me access to my dog for many months, so I took him to court. Now, after less than three weeks, I am being accused of neglect, having caused my dog an injury, and being held to ransom on time over my short weekend with him. He will not allow me to administer treatment, so is insisting I return my dog a day early and saying if I do not, I am not considering his welfare. I feel like I have no choice. And this is less than three weeks in. This could go on for years.
How do people with children cope in these situations?
I have never, ever considered myself a victim. But for the first time in my life, at my age, I think I am being bullied and it's awful.