I agree with both your posts AS smile I do this with H if I've got a family outing to go to. I ask him and if he says no or I don't know then I just go with my son anyway as if it's no big deal. I also never remind him about it. He gets one chance to go and that's it. I know he's got a bad memory but if he really wanted to go then he'd remember.
Good for you hurt to say you're going to do your own thing from now on smile It will not stop her from moving on, but it'll make her stop and think. Also don't offer her a ride anymore, she can make her own way there from now on. Treat her as if you are just housemates from now on as that what she wants to be at the moment.
You should always be nice to her and if she starts arguing then just walk away. Don't get into arguments with her. Also go around singing or humming to yourself to show her that you're happy, but don't go over the top with this. When you're going out, make an effort - sing in the shower and get dressed up even if you're only going out with mates. If she asks then just say I'm just going out with a few friends. That'll make her think as well, but make sure it's true in case she gets someone to follow you. She will be so frustrated that she doesn't know what you are doing or where you are going. She may think you're going out with a girl, but always tell the truth and don't start going out with girls. I always worry about that with my H, I've got a friend who's male but he's gay as well. My son comes with me to see him as he works at a local shop and we often pop in on our way home. I'm worried that one day he'll say to H "oh we went to see D today!". Last thing I need is a reason for H to D me.

H47 me48
T22 M21
S20 - Got high functioning autism
3/2000 H admits to OW and moves out to live with her
11/2000 H moves back home
2/4/13 H moves out
H tells me he wants D 6/13, but now he can't afford to!