Narcs are true masters of, "come closer so I can hurt you again". You drop any part of your guard however small, they see that and pounce on it to great effect.
You set boundaries and she'll ignore them particularly with reference to your point 4. Re point 3, she sees you really as a non person, someone who is there to serve her.
There is only one way to please a narcissist (and it won't please you): that is to indulge their every whim, cater to their tiniest impulses, bend to their views on every little thing. There's only one way to get decent treatment from narcissists: keep your distance. They can be pretty nice, even charming, flirtatious, and seductive, to strangers, and will flatter you shamelessly if they want something from you. When you attempt to get close to them in a normal way, they feel you are putting emotional pressure on them and they withdraw because you're too demanding. They can be positively fawning and solicitous as long as they're afraid of you, which is not most people's idea of a real fun relationship.
Run for cover when they start acting normal, maybe expressing a becoming self-doubt or even acknowledging some little fault of their own, such as saying they now realize that they haven't treated you right or that they took advantage of you before. They're just softening you up for something really nasty. These people are geniuses of "Come closer so I can slap you." Except that's not the way they think about it, if they think about it no, they're thinking, "Well, maybe you do really care about me, and, if you really care about me, then maybe you'll help me with this," only by "help" they mean do the whole thing, take total responsibility for it, including protecting and defending them and cleaning up the mess they've already made of it (which they will neglect to fill you in on because they haven't really been paying attention, have they, so how would they know??). They will not have considered for one second how much of your time it will take, how much trouble it may get you into in their behalf, that they will owe you BIG for this no, you're just going to do it all out of the goodness of your heart, which they are delighted to exploit yet again, and your virtue will be its own reward: it's supposed to just tickle you pink to be offered this generous opportunity of showing how much you love them and/or how lucky you are to be the servant of such a luminous personage. No lie they think other people do stuff for the same reason they do: to show off, to perform for an audience. That's one of the reasons they make outrageous demands, put you on the spot and create scenes in public: they're being generous they're trying to share the spotlight with you by giving you the chance to show off how absolutely stunningly devoted-to-them you are. It means that they love you; that's why they're hurt and bewildered when you angrily reject this invitation.
Sod feeling guilty as well; do you think she feels guilt?. Not a bit of it, she also has no empathy at all for you and your life either. Narcs have no empathy and their self hatred holds no bounds. She sees a kindred spirit in your ex; I think as well your mother's mad interactions with you from childhood led you into the arms of such an abuser to start with.
Be extremely careful about contact between her and your children. She also I daresay uses your children as narc supply and could well start getting to you via them.
To my mind it is not possible to have any sort of relationship with a narcissist.
What do you get out of any relationship with her anyway?. Its all completely one sided towards her. You may well be in FOG - fear obligation guilt (particularly that one) with regards to your mother. It is NOT your fault she is like this; her parents did that lot of damage to her way back.