Wow.... it's like a Pokemon cartoon, isn't it?
All these challenges, layed out before you the weight of a lifetime attached.
Honestly...... it would be hard to write fiction like this and here you are living it.
I'm so sorry this is happening to you, Lupita.
What are the odds that you'd end up dependant on the GFM at a time she wants you to lobby for something that you consider detrimental to your son?
I think you already know she's not your friend..... she's manipulative and scary scary scary in that I truly do believe she'd punish you to the best of her ability if you don't come around to her way of thinking..... and being thankful.
Having said all that...... this is the improbable hand you've been dealt.
I'm wondering if you can continue to have chats with your son about the plans he's layed out for his future and lightly speak of his plans to engage this young woman.... never mentioning a time line?
Now I'm wondering if anyone can dance
successfully with the devil...... I'm not sure it can be done but...... I'll finish my train of thought.
You can speak lightly about the future engagement, sans timeline, with everyone bc your son has already stated that was his intention.
You hope that he continues with school and career and the plans he layed out. GF will probably self destruct herself bc he's not jumping through her hoops.
GFM..... thinkingyou're NOT OPPOSED to the union, may continue to help and not sink you. That's the hope right?
If, however, you absolutely know she's going to require you start marching around demanding your son stop messing around and ask this girl to marry him..... join in girly wedding dress selection/lunch dates and viewing of swan covered Pagoda sights just perfect for a Spring Wedding......
IIIIII just don't see this going too well for ya.
You're such a nice person, Lupita.
Hard worker.
Overcomer.
Teacher of children and student of self and life.
This is a very odd situation and not everyone's life is this difficult or fraught with difficulty.
I would suggest browsing through some books on becoming more assertive, next time you're sipping coffee at the book store.
You need to be able to fence verbally with this woman so that you're not disagreeing but she doesn't realize you aren't agreeing, either.
What you say to your son, in private, will still be about respecting his plans and right to make his own decision....hoping he can stick to his guns.
Frankly, the carrot GFM dangles before you makes my mouth water for ya.

You don't want to be jerked around and manipulated, which is clearly her intent but..... it would be nice to realize your dream..... and you're worthy, Lupita.
I REALLY WANT YOU TO GET YOUR DREAM!