Yank living in Australia. 8-1/2 weeks preg with Oz citizen father. I’m on 457. Can I become AU citizen?

I’m 40 years old and on a 457 visa, but waiting for DeFacto application to be approved until after my 1st baby born due to having to wait on chest x-ray requirements. The father is Australian and British citizen and from I am from North America. Relationship not going well after a second go. I let him charm me back into a relationship and now the reality has set in and I am afraid of my mental and physical well being (due to extreme stress and anxiety that lead to depression with medication the first time we were together and consequently is now, funny enough, back AGAIN!) I NOW refuse to live together as a couple due to my partners mental abuse to me (a pattern in all of his relationships) One afternoon, his friends shook their finger at me and said” I heard you were dancing with the devil again” and warned me to stay away from my partner as he strings along women and mentally breaks them down, verbally abuses and screws up all the women he dates They all leave the relationship in a devastated state. His best friends (our friends) respect me as I have known them (some longer than my partner) and told me to remember it was NOT ME, but HIM that was f***** up and to walk away while I still could. After this conversation, I left on holiday for 10 days and came back to my original senses (like the first time) and was going to break it off, but found out after my holiday and the day I was going to break everything off with my partner that I was pregnant!

I am really confused. I really want this baby, but do not want him to be a part of the process anymore. In his abusive anger, he had several times discussed our pregnancy as his regret and a mistake and we should consider the “other” option. The thing I forgot to mention above was that getting pregnant was his WHOLE idea from the beginning!!!!! He did not stop thinking about it for months and tricked me into it one night. I know now it was his way of trying to make us a complete couple again. He lives in a fantasy movie. Now he is Blackmailing me into saying that if we can not live as a couple in bringing up a child together like a married couple, then he thinks we need to and I need to leave Australia. Also, now he says that I tricked him into going defacto!!!!!!! EVERYTHING WAS HIS IDEA!!! I need help and my head is spinning with hormones and my second depressive episode EVER!!! (Both depressive episodes due to the same guy at the same timing in the relationship-certainly a pattern here!)

What I want?-I want this baby, but do not really want his involvement. He will cause the same mental abuse to our child. He is toxic to all relationships and he hates is own father! (as he is repeating the same patterns of his father)

Do I leave Australia and have the baby in my own country and try to legally keep the father out of our lives and save me and my baby’s lifetime of abuse, legal fees, time, money, unhappiness and custody struggles?

I am 40 years old with no children and my partner is 47 with 3 careless previous abortions/miscarriages. Biologically, time is not running in my favor, but only took me one month to get pregnant the first time. I am strong mentally and physically woman that looks younger than I am. I run marathons, have a successful IT career, have an awesome support of family and friends back in the UK and am one of those people that can easily do anything I put my mind to. I have not doubt that I can do this on my own and KNOW that my child would be better off without his cheating, deceitful biological father involved. But I am quickly finding out that the father’s blackmails have turned into legal discussions behind my back. He is threatening to serve me with legal papers and to call my mother if I do not agree to make a final decision with him by the end for the week and spill the news before I have a chance to discuss with my family. My family is EXTREMELY religious and need to hear this from me face to face when I am home next month and I need to handle this situation very carefully. My parents do not need to hear this from someone they have never met ever before and especially over the phone.!!!!
I am looking for an agressive family custody law specialist here in Australia or in the United States if anyone has any recommendations. Mine and my babies life-long health depends on it. If I have to abort, then it would be better on both me and my child than to have to live with the results of his mental abuse and emotional blockage that the father is not willing to acknowledge or begin to explore and for us to have to only pass down to another generation! The buck stops here one way or another!!!

Any and all advice, positive or negative is welcome!

Thank you very much for your assistance and advice in advance!!!!!