This is gonna be lengthy -- I'm really sorry about that, but there's a lot to get through -- and anyone who takes the time to read all of this has my sincerest thanks in advance. I have no clue what else there is to do and I'm tearing myself up stressing about this, but I have not yet acquired a therapist because unfortunately, healthcare is expensive, so this is the next best thing.

I'm 24, she's 22, and my dad is 54, and I just found out they've been dating for 3 years now, before he divorced my step-mom, which was last year. Strangely enough, the age difference (more specifically, the thought of potentially having to refer to someone the same age as my little brother as "stepmom") isn't what bothers me, at least, not nearly as much as what I found out less than a week ago from her (let's call her Ann), while my dad was out.

Ann told me this in tears,

But I have to back up. After my mom and dad divorced 20 years ago, not long after my mom gave birth to my little brother (my older brother was about 7 and I was 3 or 4). Since my parents separated, he's gone through at least 2 girlfriends in the US that I know of, my current stepmom, who officially divorced him in 2013 and had a daughter with him, who's now almost 13, and now 22 year old Ann-not-Ann. I have another half-sister from the woman he was with before my mom (they weren't married), and I also found out a couple of years ago about yet ANOTHER half-brother from another woman in the Philippines -- this kid would've been born between the time my parents separated and dad married my stepmom in 2001, and in all probability, conceived when dad went to visit the country again (dad was born there). He continues to deny that the son is his and refuses to be DNA tested, even though the boy looks exactly like my dad did as a child, and the mother is trying to sue him for child support, but we don't really keep touch with her or her son. If all this evidence of his womanizing behavior wasn't enough, let me tell you, I've had enough conversations with him to know exactly how he views women, and he's made it abundantly clear that he believes women are inferior and should obey men in relationships -- or, you know, his version of what a relationship should be, in addition to everything else that's wrong with him.

My parents separated because

Back to the situation at hand, he basically abandoned his adolescent daughter and recent ex-wife at least a couple of years ago to go spend his early-retirement money in the Philippines the majority of the year -- like I said, he has dual citizenship now -- not caring at all about how this sudden change affects his daughter. The Philippines is where he met Ann, his current 22 year old girlfriend (he had not yet been divorced from my step-mom when they started dating though). I returned to the US about a week ago from this visit, and Ann told me of what he did on the last day of my trip. My dad returned the US two days after I did, and so Ann is still in the Philippines staying in his 3-story house while he's gone. She has tried to leave him once, but of course, he begged her to take him back, and while I have been trying as best as I can to convince her to leave, preferably before he returns to the Philippines and is able to beg, she is having a really hard time convincing herself to leave him, and she misses him already, even though she confessed that she was afraid of him now. She wanted to finish her studies before they ever started dating, except my dad told her not to, he said it's because she wouldn't need to get a job with the all money he has (I'm realizing now that this is all a part of his plan to trap her in this relationship financially), and she's so young. We became good friends while I was there, and I see her almost as a sister now, which is still pretty weird to think about because she's the same age as little brother and is dating my dad, but the point is, I care very much about her well-being -- she's so sweet and understanding and trusting, and I don't want to see her end up the same way my mom did. I don't want her to spend years being bitter and angry and recovering from the aftereffects of his mistakes because he doesn't want to deal with his own abusive past, but I feel so helpless not being able to do anything for her except try to be as persuasive as I can and just be available for her if she needs to talk.

Worse still, I don't think I've ever been so angry at my dad in my life, but I can't even get angry at him because being honest with him could give Ann away, which could end up dangerously for her, and all I want to do is get angry at him. I want to tell him to **** off and then never see or talk to him again. I feel like all my efforts to have a quasi-normal relationship with him over the past 20 years, all the work it's taken for me to try to forgive him for what he did in the past, have been for nothing, because apparently he hasn't changed at all, and I may never actually have any sort of real relationship with him, which hurts so much. But I am so beyond tired of all his ********, and I don't want to deal with it anymore. But I don't know how to act around him, and I'm bound to be have to be around him sometimes, because his side of the family is really big, and my cousins and siblings are close, and he'll occasionally text me to ask how I'm doing (his responses are typically one word answers). I guess I have enough practice pretending that we're best friends that it shouldn't be too difficult to do it for Ann's sake, but in the meantime, I'm having a time trying to cope with all these feelings. I'm trying to focus on moving out of my mom's house next week for now, but I can't even bring myself to finish packing.

I don't know what to do. I don't know if I can actually do anything about this. But I would really appreciate some support, if nothing else. My brothers are a lot like my dad in many ways, and they haven't been the most supportive about this.

Thanks again for reading.