Hi there. No, you are not a nut job for staying--- this is your family you've invested almost 3 decades into. And you love her. I'm not sure about this situation of her telling you she loves her x. This may be whimsical thinking on her part but is a sign that she has unhappiness in your relationship too. What about counseling for the two of you? It does boil down to a bigger picture than your lack of sex. That appears to be a symptom of other issues. Working on the other issues may improve your sex life.
I agree that the lack of sex may be a symptom of other issues in your marriage. The best way to deal with this is to go to marriage counseling and get to know what the other is thinking. Please consider this as an option, and let us know what she thinks about it. She may be really happy that you came up with the idea. It might be something that she's considered, but was afraid to ask for.
in the meantime, you could try to be more intimate with her outside the bedroom. Make it a priority to spend time with her, and let her know you want to make things better. It' would be a good start.
Forget about her other boyfriends, ie. how many. What does it matter really? Frankly, after 20 it's probably hard to keep specific count. Who knows if she ever even knew their right name. That was then , this is now.
It's not a good sign that on your birthday she talks about another man. It shows she's become insensitive to your feelings. Have you been insensitive about her feelings? and could it be that this was her way of getting back at you for doing so?
Maybe you could ask her if you both could write each other a letter to talk about how you feel about your marriage? It might open the lines of communication and make life better.
It's great that you reminded her that it was your anniversary. Some people don't feel the need to celebrate anniversaries, however, making the suggestion to make an anniversary celebration a tradition is charming, and i'm sure she'll come to appreciate it in years to come.
Too bad counseling is taboo, however, you can get around that by finding some good books to read, and bringing up some of the finer points in conversation.
Also, why don't you go to a therapist to handle the problems that you're having. ie. you wanting to talk about her boyfriends. I'm wondering what came first the chicken or the egg. You say that she said she still loved her ex (I still love a couple of my exes, but those ships have sailed) on your birthday. Do you think that she told you that because of you questioning her about her boyfriends ? I mean if she doesn't want to talk about her old boyfriends are you are obsessive about talking about her boyfriends, maybe she told you she loved one of her boyfriends because she was angry and getting back at you for being so (in her mind , overly) inquisitive?
As i said, if asked, i would also have to say i still loved some men in my past. I don't think that love changes. If you love someone, you love someone. You may not be compatible with them, or you may not be "in love" or wanting to express your love sexually, but once you love the essence of a human being, i don't think it goes away. All kinds of people get divorced stating "irreconcilable differences", as opposed to "don't love them anymore".
Yeah, my best advice if i were in your circumstances, is that i would go and talk it out with a therapist. And i would take up her slack, by reading on the subject and maybe finding content that would help her to get closer to you. Your therapist will also give you advice as to how to handle your marriage. You've got all this on your plate, alone. Why not find a therapist to help you deal with it all?