Would this be too weird?

[YOLO66]

Several years back, I have relations with another guy.  At the the time he was in the "curious" bracket.  It was fun and for a while he kept the relationship going.  Ultimately he too was more hetero than not, and also wanted the white picket fence.  He found a nice lady, became monogamous, eventually married and is living happily ever after.  
Like any old friendship, we stayed in contact, occasionally hung out with mutual mates, etc.  

He was completely honest and upfront with his eventual wife, almost from the very start.  That's why he became (and stayed) monogamous.
His wife seems lovely.  She knows who I am, and what our relationship was.

I went to their wedding, but fortunately only as one of many guests and I didn't have to make smalltalk with the happy couple.

The first time she tried to friend me on fb, I ignored it for a while.  But she messaged me, said there was nothing to be awkward about, and even make a joke.  So we've been fb freinds, and since then she has been the usual fb chatty.

But recently she has stepped it up, keeps saying we should all catch up, etc.  And now has culminated in a personal invite to a small gathering for his birthday.

I'll be honest, I'm freaking out a bit.  And I'm not really sure what her motivation is?  
It's great that she's apparently so accepting and unfussed by his past.  But still, why reach out to an old friend from years ago???
Is she trying to slay old ghosts?  Does she want to embarrass us?
In the past she has made "jokes" such as her being so beautiful she turned a gay man straight.  Is that what she wants to prove?  
Or worse?  From the beginning she has made jokes that I took as lovely attempts to make light of the past and bridge the gap.  All accompanied by plenty of "lol"s and smiley faces.
But the more I think about it, the more I think these are not the kind of jokes a woman makes?
"When I have a headache my husband should call you."  "We should have a 3-way because I don't like sucking his ____ but he says you were really good at it."  etc
I am half scared she was serious, and half scared she was being angrily sarcastic.  I imagine walking in and being introduced as the man who used to ____ her busband like a little bitch.

If it were just me, I could take it, simply because I can turn around walk out and never see them again.
But what if she is planning to embarrass him?

[salparadise]

Yea, I think it's weird. Perhaps she is just open minded and means no harm, but he probably doesn't want the whole world to know the history. And she's likely to spill it, in fact, she seems determined to. The history is between you and he, but she is inserting herself as if it's her history too, and for some strange, unknown reason it seems she is trying to get something started up again. Maybe it turns her on. If I were you I'd ask him and take the cues from what he says.

[Ellener]

Just politely say no thanks, and ignore her. And him probably. It's the past.

[Maddieandtae]

I think she just wants a threesome with you and her husband and is testing the waters before coming right out and asking!