If It's Not One Kid...

So I get an email from my daughter this morning, which I sometimes do when she passes things along to me. Subject line was something to help me & DH with DS becoming more independent. The link was from the "Empowering Parents" website. (I didn't even click on it, because I've already looked at that years ago & it's a money-making scam.)
Then she goes into a paragraph-long tirade how DS is going to live with us till he's 40, playing trading cards, etc etc & don't tell her that we're managing that because it's "bullcrap." (To be honest, I haven't looked at the email since I forwarded it to DH, per her request. It's way too triggering right now.) So now I'm mad at her.
First of all, an email to say this? Really? Yes, I think she has issues with confrontation, but still... This is NOT an email-type subject.
Second, she had NO IDEA the lengths I've gone to with DS. The doctors we've seen, the administration that I've dealth with, the legal issues I've headed off, all the websites & books I've consulted (including the one she sent me). NO IDEA. Nor does she need to know. It's not about her & never was. I guess she thinks I'm stupid?
Third, she had no children of her own, so what the ____ does she know about parenting? (Yes, I know that teenagers think they know everything; I did too at that age.) You can lead a horse to water, but you can't make him drink. Believe me, short of putting a gun to DS's head (which I wouldn't do anyway), I've influenced him in every way I know. I'm at the point where he is an adult that needs to make his own decisions about his own life; it's not up to me anymore.
Fourth, what DS does or does not do has no bearing on what she needs/wants to do with her life. Even if he was perfect, does that impact on what she does next in her life? No. Bottom line: his problem is NOT her problem, nor is it any of her business. And no, she isn't saying this out of concern for him. If she were, that would be a different story...And if she were, she isn't telling HIM (the one she has the problem with) this.
I am insulted. I feel like, "how dare she!" Yes, I know I'm not perfect; maybe I could have made different decisions than what I've made. But I did the best I could with what I have & what I know. Sorry if that's not good enough.
Will I say anything? I have a feeling that DH will probably chew her out, so she doesn't need me laying into her as well. Right here, I'm just clarifying my feelings.