Mail: Forwarding: Original Sender Gets Email as Well?

Question

I haven't been using Mail very long -- I used to use Eudora for decades and it was my definitely favorite email app. I hated Outlook et. al and when I bought my MacBook Pro and it was running 10.5.8, well, I just could not get Eudora to work. So I reluctantly had to switch to Mail, which I hated then, and hate even more now.
A couple of times, I was horrified to see that when I forwarded email from someone to my wife, and perhaps added a comment with the quoted text of the email, the original sender whose email i was forwarding got the email -- with my comment -- as well!
Since I don't know what's going on, I don't know how to explain it, but here's an example. Someone emailed me about taking some lessons (I teach Japanese). I replied and said I couldn't take her right now, which wasn't true -- she was already asking for a group discount for two people and I know the type and I just didn't want to bother with it, so I said I was too busy.
Then, I forwarded the email she had sent me, with the request for the discount, to my wife. I specifically chose the "Forward" button, my wife's address appeared in the address box, and I included some snide comment about why the woman was asking for a discount on a discount, as I'm already way cheaper than most turors.
Still with me?
Then, later on I changed my mind and replied to the woman and told her I could fit her in, but she'd have to pay the full price. I BCCd my wife in on this email (Bcc means "Blind CC" -- meaning, as I understand it, that the main person recieving the email only sees their address in the header, and possibly "and other recipients," but not anyone else's email address or anything like that.
So, we go back and forth over various things, and occasionally I forward the woman's email to my wife, again, with comments, that I OBVIOUSLY don't want this woman to see.
Okay, no problems there -- before I click "Send" I make sure my wife's address, and ONLY her address, is in the address field, as I'm just forwarding an email.
Yet today, when I went to check what time this person is coming, I see all the emails that we've ever exchanged including the very first one, all one after another -- her emails, my replies etc. But then, in the middle of all these, I suddenly see the email I forwarded to my wife with the snide comment in it! How the **** did it get in there, and is it possible that email was also sent to this woman as well, so she read my comment?
Other odd things have happened when I've forwarded things to my wife -- a reply, perhaps, from someone we both know but with my previous emails, NOT MEANT to be read by my wife, somehow in the chain!
Now I'm ultra paranoid. Has this woman received those emails I sent to my wife (I thought) and read my snide comments? Why on erth would Mail include, in this bck and forth with this woman -- maybe ten emails in all, suddenly a forwarded email to my wife? It should not be in the chain at all, since it was NOT sent to the woman, merely forwarded to my wife.
Is Mail sending emails to people with their email addresses being visible in the address fields without my knowledge? Has this woman read my snide comments (and my wife's replies to them!) and even if not, why are those back-and-forths with my wife doing in the same chain as the emails to this woman? They technically should have no connection to the woman, since they were nit addressed to her, merely forwarded.
And are people seeing who I'm Blind CCing? Mail certainly is an effed-up app -- it's very badly putr together and just serves to remind me that Apple has really put some horrific software into their systems over the years, and seemingly with every new iteratioon and every new OS, the apps just get worse and less intuitive, not the opposite, with NO WAY to downgrade. If I had my way, this MacBook would be running Tiger. with iMovie from 2004 (same for all the iLife apps -- they've degenerated into Microsoft-like unusable messes).
But I'm seriously worried about this Mail issue -- the last thing I want is for people to be receiving emails that I'm not aware are being sent.
And I REALLY wish Eudora functioned on this machine -- I don't know why it doesn't but it keeps giving me error messages. But that's a separate problem.
Anyone else experienced anything like this?

Answer 1

Thanks, guys . . .
I kind of knew that Mail couldn't possibly be sending emails to people without my being aware of it but I just wanted to double check.
As far as the other email programs go, for some insane reason all the ones I try (Thunderbird, for one) have problems connecting with my SMTP (outgoing) server. In one case, there's no way to change my account setting from IMAP to POP . . . the way these programs are set up, just configuring your settings requires a B.S. in network technology . . . every time these things happen, I end up on the phone with the local ISP for two hours and most of them have no idea what a Mac is  . . .
I think in this case I wll just stick wth the Devil I Know. Every email program has its drawbacks and Mail is clunky and unintuitive but thank God, it integrates with SpamSieve, the only junk mail killer that really, really works (I just learned how WELL it works when I tried Thunderbird and it downloaded all the mail I'm REALLY getting s opposed to the mail that I end up seeing -- for every legit email that SpamSieve lets through, there are at least 75 that it doesn't. I don't know about anyone else, but I'm inundated with at LEAST 400 junk emails A DAY for my two accounts and without SpamSieve I'd be in the First Circle of ****, but I digress).
It's been a year now with Mail and although I despise it at least now I think I'm getting used to it, and your reassurances about people getting unwanted mail definitely removed my last doubts.
I'll stick with Mail, since the others don't look exactly like champs either, and just pray Apple doesn't "Upsdate" anything for a good long while.
Cheers, mates
Nick