The trouble with being the gay son

For most of my life, my mother has treated me more like her girlfriend than her son. She's always clued me in on what (but mostly who) is making her life unhappy, and I think I learned from her a sense of never being satisfied with anything, because neither of us ever are. However, since I graduated from college, Momma has been really relying on me as an adult-to-give-advice, and the respectable distance usually present in mother-son relationships is quickly diminishing in ours.

Now, I'm not complaining that my mother feels like she can talk to me. I want her to be able to, and I like being able to talk to her about most things (I still avoid discussing my sex life and religious beliefs with her). However, I feel like our roles have been reversed too soon for my comfort. I'm 22. I still need to go to her for advice about life, but instead she's coming to me, not necessarily for advice, but to vent. She hates her coworkers. She is planning to leave my step father (she has been for 10 years and still hasn't managed to). She thinks she would have been happier had she never divorced my father. It's kind of weird to hear my mom say these things. They show that she's a human being who makes and lives with mistakes. While I don't deify my mother, I realize she's a person and she messes up, I'm still bothered by her calls 3-4 times a week to inform me her husband got drunk and they fought again last night or my older brother is having a rough time at work.
I think these calls upset me because there's nothing I can do to make any of it better. I can't make my stepfather stop drinking, I can't make my mom's co-workers give her the respect she deserves, I can't find my brother a job closer to home, a girlfriend, a constructive hobby. Hell, I have a hard time making myself believe my life is headed in the direction I want it to be. And that's tough for me to deal with. I feel a strong sense of piety toward my family, and I'd sacrifice what I could for them. It's just the Southerner in me. I'm a fixer, I know this. But I'm up here, she's down there, and I can't fix anything. Granted, I wouldn't be able to fix anything if I was right beside her. I feel badly for her. She's stuck in a marriage she doesn't like but will never get out of, for whatever reasons--guilt, familiarity, financial dependence. She hasn't got many friends, and the ones she does have are in no better situations than she is. So, she comes to me, because she knows she can, that I will love her regardless, and that I'll listen, even if only because I'll feel guilty if I don't. And that's the trouble with being the gay son.
I really hope that I can be like my mother in a lot of ways. I'm proud of her work ethic and her nurturing ability. I value her wisdom and integrity, and one day I hope I have just as much of both. But I really hope I don't find myself in the same relationship strifes that seem to plague her life.