Agree with Elsa - your dad's wife isn't the problem here.
Your father CHOSE to leave, to take no interest in you and not to pay any maintenance for your keep. If he had cared about you, he would have told his wife that you were his responsibility, and whether she liked it or not, he was going to look after you (btw - 10-odd years ago she would have been eligible for a student loan, and she was living at home, wth him).
If your dad was a violent alcoholic when he was with your DM, then he will be a violent alcoholic with this woman. She is possibly unable to work because he is controlling and won't let her, or makes sure that she loses her jobs; he may be jealous of her intelligence and make it difficult to get a job in her chosen field (just out of interest - what is her degree).
He very probably has eaten away at her self-esteem and mental and physical health over the years, and made her emotionally and financially dependent upon him. He may seem to be the one who is badly-done-to to you, but domestic abusers have a great gift of playing the victim, and coming across as charming and salt-of-the-earth. It is always their partner's fault, and they are the ones who are really suffering. They are narcissistic, egotistic and manipulative. Even now, he is putting the blame on his wife for neglecting you and leaving your mother - he is taking no responsibility himself. He was a grown-man. This woman didn't pull a gun on him - he CHOSE to leave, and he CHOSE to act as though he had no child - remember that. Everything was HIS CHOICE.
Personally, I wouldn't have bothered looking him up, but I can see why you might want to know where you've "come from"- You are playing into his hands here. It suits him to come across as a family man now, and probably brag about his DGD to his friends - and it's something he can rub his present wife's nose in. No wonder she is aggressive towards you.
He will turn on you one day - or when you are settled and financially secure he will borrow money off you, or emotionally manipulate you and your child.
Remember who has love and struggled and looked after you all of your life. Your MUM. Remember who has done a lot for you and your daughter - YOUR STEPFATHER.
These are the people who love you and who care for you and who you can tryst. They are also the people you are probably hurting very much by being so involved and impressed with your waste-of-space father.
I promise you, that this man will not bring long-term joy into your life. He is a manipulative user.