Is OTHER wrong in the post ? POST : Now hear me out. I know that sounds terrible. 

According to my boyfriend, he lived with his mother until he was about 8. He would visit his father on occasion, and one day while his father was dropping him back off to his mother's house, they found no one home. His father then told my boyfriend that he would now be living with him. That was one of the last times my boyfriend had seen his mother in person.

And now, about a year ago, my boyfriend got a hold of his mother's phone number. A few text exchanges, and then a few happy phone calls, and my boyfriend was so happy to have his mother back. My boyfriend is a very very loving guy and loves my own mother like his own, so I could tell he was so happy to have his own mother back. 

A few weeks later, literally the night before his birthday, she said, "I love you and I'll call you and send you a present tomorrow," to him. Then, she ghosted for months. And I could see my boyfriend becoming so sad because of it. He didn't talk about it, and if I brought it up he would get quiet and not say anything. He had already been abandoned by her once before. 

I ended up texting her myself and I did chew her out. I wasn't mean, but I told her she's missing out on the most sweet boy she would ever meet and that I would pay for her phone bill, stamps, whatever she needs to at the very least send him a text. I implied that if she can't at least do that, then my boyfriend and I would not contact her again. No response from her. 

6 months later, a text. She tells him that she loves him and she is sorry, and that she won't leave him again. And she admired me for getting mad at her, actually. And that she will be contacting him again soon with a call. 

He doesn't hear from her for about a month. Christmas rolls around, and I ask my boyfriend if he wants to send her a merry Christmas text. He shyly says yes, but he asks me if I can do it because he's too scared to. 
This isn't the first time he's asked me to text her for him. He wants me to do it so he doesn't have to face the facts of getting nothing in return as directly. I had texted her multiple times at this point.

Can you guess what happens next? Yup, nothing.  And that brings us to the current point. 

Am I the asshole for wanting to cut her out, even if she sends us a text in the future? I hate seeing this pattern of him getting filled with love for her then getting his poor heart ripped out. I want to say so many mean things to her and I want to be nasty, it takes all of me to not be mean. I would be open to her coming back if I see massive change but it would take some effort on her part. 

TLDR; 
My boyfriend's mother who left him at the age of 8 came back into his life. She will get him hopeful that he can have a mother presence in his life again by calling him and making promises and then rip his heart out by not responding to any texts or calls. Am I the asshole for wanting to cut her out? 