Is my friendship toxic?

My best friend seems to find fault with me every few months. Our friendship has been long distance for the last 6 years, and when we're chugging along good, it's really good! But I'm starting to resent her for finding issues with how I'm not being a good enough friend to her. 
She is single and I got married last November. The latest saga: she's just cut off contact with a guy she was messaging for nine months who she has known for 12 years and used to be really good friends with. They committed themselves to each other when they reconnected last year (via long distance) until she moves back to the same country as him (early next year). He's done nothing but treat her like shit since - ignore her messages but spend all day updating his social media, use stupid excuses for his silence, get defensive when she asks him what's going on etc etc. It's been a horrible cycle of her being upset > angry > confronting him > cutting him off > letting him in again > being happy > and repeat. It's exhausting for me to try to support her through it each time because she doesn't seem to learn or want to let go, and she deserves so much better. 
Three weeks ago she cut him off for good (she says). Since then she'll send me screenshots of him liking her social media posts or messaging. I respond with anger and frustration because it seems that, now that she's not attainable, he has some time to spend on her, and that's just a massive dick move in my book. We have a bitch about him and move on. 
This past weekend, I get a message from her telling me that I'm not being supportive of her and her feelings while she's going through this break-up. That all I do is bitch about this guy and how much of a dick he is, which leaves her still feeling hurt and rejected. And that I should know that I need to ask her if she's okay and that's all I need to do. 
Here are my issues:
- he is an arsehole
- her stalking him on social media is not a great way to move on
- I'm sick of this cycle
- I am her main support person, but she isn't mine
- I've never had to help her (or anyone) through a break-up before
- I've never experienced a break-up before
- I'm pregnant and dealing with all the fun issues that go with that
- my grandmother has just been diagnosed with a terminal illness
- my current work situation is causing me anxiety and panic attacks 
Now, I'm not in any way alluding to my issues being any more important than what she's going through right now. And even though her messages to me have made me angry and defensive, once you take away all of the emotion and bullshit, at the end of the day, she is asking me for more support and I feel that that is something that, as a friend, I cannot refuse. 
I messaged her back and vowed to try to be a better friend for her, and didn't get a response. So 24 hours later I sent her a message asking her how her weekend was going. Again, no response. 
Now the resentment has started to kick in, and I'm feeling angry and hurt. How dare she say I'm not being a food enough friend after everything I've helped her through?! After being on Facetime to her, listening to her sobbing when, earlier on in her "relationship" with this guy she was hurt and destroyed. Telling her she deserves better and she is not the issue. Pointing out why his behaviour is bad and shows that he isn't making her a priority. Sending her flowers to cheer up...
I just don't really know where to go from here. ☹️