Would you do this to your child?

I am so sick of Jenna's crap.
Little backstory here: my boyfriend has two kids from two previous relationships, Ava and Emily.
Jenna is Emily's mother, Kathleen is Ava's.

Now my boyfriend gets his kids maybe twice a month. Every other weekend, Ava comes over, and she'll spend the weekend with us. Up until a few weeks ago, Emily did too.

Jenna is now saying that she doesn't want Emily around Ava.

I know I can't say anything, because Emily is not my child. It's not my place to say anything. That is between my boyfriend and Jenna to work it out. But my boyfriend won't do anything about it. It bothers me that he won't, but I understand why. Jenna has bi-polar mood disorder and she doesn't handle stress well. When my boyfriend and Jenna were together, she would verbally abuse him. It never got physical between them, but it took a lot for him to just open up to me after he ended the relationship with Jenna. I understand he's scared that maybe when Jenna is stressed out and angry, she may take it out on Emily, but not letting my boyfriend see his kids, it hurts me. I know he loves his kids more than anything in this world. He pays $800 a month in child support and he's only allowed to see them every other weekend.

Even Kathleen, Ava's mom thinks it's stupid. Besides Jenna, I'm the only other woman he's introduced Ava to. Ava and Emily love me. Emily loves being with her sister, but now Jenna is keeping her away.

I know I can't say anything but holy shit, it bothers me so much. It kills my boyfriend that he doesn't get to see his kids. I know he doesn't wanna stress Jenna out, but christ, he deserves to see his kids. He's not some deadbeat. He pays his child support on time every month and he's not even supposed to do that because there's no court order. He's just doing it because he knows his kids need it.

And I hate to say it, but I honestly think Jenna is letting Emily call some other guy daddy. The last time she came over, she wouldn't call my boyfriend daddy. She called him her "friend".
Do you know how crushing that is? That was the first time I've ever seen my boyfriend cry. It hurt him so much.

So seriously ladies, if you and your man break up and you have a kid between you, let him see his kid. Don't sit there and keep the kid you made together away from their father. I know when Emily grows up, she's going to have hard feelings against her mother because her mother is keeping her away from her dad and sister. Even Ava doesn't like Jenna anymore and she adored Jenna, it took Ava forever to warm up to me because she was used to Jenna being around, not me.

I couldn't ever do something like this to my kids. I just couldn't. I myself have hard feelings against my mom because she kept me away from my older brother. I've only met him twice in my whole life because my mom kept me away from him.

I just hope Jenna realizes her mistake before it's too late.