His psycho clingy female friend--am I underestimating her?

Where to start... when the boyfriend (30 yrs old) went official with me (26 yrs old), his friend "Dana" (we'll call her that) (24 yrs old) broke down and confessed her love for him. Then she saw he wouldn't budge and she de-friended him on Facebook. Then she re-friended him and told her she didn't mean what she said about loving him.

It gets better, though. About two weeks after Boyfriend and I go official, Dana started dating some other guy who had his eye on her for months... yet the strange behavior continued.

It seems evident to me she was crazy about my guy for a long time but he wouldn't reciprocate. Before I came along, she gave him a spare key to her apartment "in case of an emergency (or whatever)" (No, he didn't give her his key in return) and set up a Sam's club membership with him. She gave him the password to her Netflix account. But what gets me is that this behavior pretty much continued even after my boyfriend and I MOVED IN together.

For example, she kept sending little baggies of candy home with my guy. And she got this bag of candy bars for Christmas and insisted that my boyfriend take them home and dole them out to her one by one whenever she asked, since she "couldn't trust herself" to have all of them in her possession. (Yeah--why didn't she send them home with her own man?) Then she insisted he read some of her books--on her kindle--which she sent home with him.

And the occasional times when she and her boyrfriend and I and my boyfriend are in the same room together, she directs all of her attention to my boyfriend (surprise) while her poor guy sits and sulks.

It all kind of culminated when she had my guy over at her place, alone, until 11:00 pm to discuss with him her interest in changing career tracks and getting a new degree in his field (surprise!). At this point, I told him that he could be friends with whomever he wanted to be friends with--but the least he could do is avoid the appearance of infidelity, set some boundaries with her, and send me a text message if he's going to be out after 10:00 pm.

Thereafter, he did send her a nasty email asking her to recognize they were both in relationships and should act like it, right after she called him a jackass in public for not going on a hike with her like they had planned to do six months before they were involved with other people.

Sorry for the rant. My assessment is:

1. The guy she's with is a rebound and/or beard (i.e., someone she's dating to conceal that she still isn't over the guy I'm now dating).
2. I should trust her as far as I can throw her, despite her syrupy sweetness toward me.
3. I don't want to start dictating terms to my boyfriend... but should I be more iron-fisted about this? He said he's never been interested in her and I believe it--but she doesn't have to steal his heart and live happily ever after with him to get him to commit one indiscretion in a time of weakness... or to just plain annoy me and make my life unpleasant whenever she's around.

And should I be lenient with my guy, like I have been? He's brilliant, sure (an engineer!), but really not very socially perceptive.

Thoughts please?

She has definitely got some issues and it sounds like she is wanting to do anything she can to get the attention of your man. But your ma isn't doing much in the way of putting her off either. If she keeps doing these things he's either being too nice or he's giving her some signals that it's ok to do all of this. Sending one email telling her off isn't enough. If she's doing all this, why hasn't he stopped contact with her? He obviously knows how she feels and why would you stay around someone like that if your happy in your current relationship?

Maybe he isn't interested, but he sure is fueling some of this and that needs to stop!

I think the fact that he's told her that she needs to respect the fact that the two of them now have significant others was a huge step to show her that her behaviour is inappropriate so, good on him for doing that willingly, without you having to cause drama to get him to straighten her out.

Perhaps you should have a sit down with him and just tell him that the two of them (if they even are) meeting up one-on-one now that they both have partners is inappropriate and disrespectful to you and her new guy... which IMO it certainly is. They've been friends for a while, which is fine (you shouldn't have to demand that he stop a friendship but the dynamics of that friendship should change now that you and he are in a committed relationship.

I have a feeling he won't fight you on too much when it comes to telling her to back off and (to be honest) get real...

Good luck.