Single Dad Advice?

TL;DR
My mind is currently in a state of insanity at this point. It has been approximately three months since I (M36) last communicated with my pregnant ex-girlfriend (F34)…or in this case, since she's communicated with me. In any usual story that you'll hear or read, it's always the dad that runs away from his problems and responsibilities, but not this one. I have been consistently attempting to reach out to my ex through phone calls and text messages just about every day. However, she's blocked my phone number and has muted all my notifications on FB Messenger. The only responses I have received are two text messages requesting me to cease calling her and expressing her disinterest in conversation with me.

It's important to note that we do not live together. Three months ago, on a Monday morning, she called me and told me she was experiencing some abdominal pain (she was approximately 13 weeks pregnant). Mind you, I was up all night and went to the gym, so when I got home, I showered and slept. Her phone call came in about 2 or 3 hours later. She informed me of the abdominal pain and that she was going to schedule a doctor's appointment and call me back. I told her I would answer when she did. Regrettably, I didn't take into account that her doctor's appointment was going to be that same day on short notice. I usually sleep with my phone on silent before bed, so she asked me to turn the ringer on my phone back on after our conversation. Believing that I had already done so, I put the phone back on my nightstand and went back to sleep.

As a result of me thinking I did turn the ringer on, I missed three additional calls from her. When I finally woke up about three hours later, I discovered the missed calls and immediately called her back, but she was already at her doctor's appointment with her mother.vDuring our brief phone conversation, I asked if there was anything I could help her with, but she declined. After the call, I made sure that my ringer was turned on this time around, which it was, and we spoke again a few hours later after her appointment. She reassured me that she was doing well. I asked if I could call her later that evening when I went to work, and she agreed.

However, when we spoke later that night, our conversation was initially pretty normal and good, but once I deeply apologized for missing her calls, her demeanor took a complete 180. She expressed disappointment and frustration toward me. I acknowledged my honest-to-God mistake and apologized sincerely, explaining that I genuinely believed I had turned on my ringer but had inadvertently failed to do so. She then began yelling at me, saying, "What if we lost the baby, and I had to break that news to you over the phone, and my mom was here to hear it instead? My mom says you not being there wasn't a good look for you." So I tried explaining to her, "I get you're upset, and I'm not saying what happened on my end was excusable, but the way you're angry, you're coming at me as if I didn't want to be there." I had to end our phone conversation early because I had to return to my work duties, but I promised to call her back later to talk more about that day's events, but she said no. So, I sent her a long text message apologizing for the miscommunication.

Since that Monday night, I have been unable to speak with her on the phone. She hasn't read my texts and has muted all my calls. The only text messages I have received are "I don't want to talk" and "Stop calling me."" This situation has taken a significant toll on my mental well-being. We were expecting to learn the gender of our baby through blood work that she underwent that Monday morning, so I believe she already knows the gender of our child as I write this, but I still remain unaware of the results. Deep down, I fear that she may no longer wish to have any involvement with me and is purposely keeping me away.

While I understand that my lack of actions may have contributed to this situation, the lack of communication has left me feeling uncertain and anxious. The possibility of enduring weeks or even months without any form of contact is a genuinely scary thought. I genuinely feel deep down that this could have happened to any person. I went to her house two weeks ago to deliver a letter telling her that I want to be a part of this baby's life and to please not rob me or my family of the opportunity to be a part of our child's life. (I was respectful and didn't curse her out or anything in the letter.) Again, that was two weeks ago (at the time of this writing) that I delivered that letter to her door, and I still haven't heard anything back. Want to know another crazy thing? I'm STILL her friend on Facebook, but yet I'm blocked from seeing her statuses dated from the day she went to the hospital.

Just recently, she posted an updated sonogram of our baby as her Facebook cover photo, but yet I haven't heard from her in three months. I want to comment on that photo so badly, but I feel like if I do, it's just going to cause future trouble for me, so I refrain from it. I've been told to screenshot every call and message to her, which I have. I'm desperate here. I've never been physically abusive. I've never spoken cruelly to her during her pregnancy. Yes, we had our fair share of back-and-forth arguments, but what couple hasn't? I'm really struggling right now with what to do. My 15-year-old son sees how hard things are for me, and he doesn't want me to give up. It means so much to have his support. I'm not kidding; I'm desperate. Any advice you all can give me would be amazing.