Background: Im 38 weeks pregnant, MIL lives across country and has a huge history of being dramatic and making everything about herself and she's at it again

Alright, so, a month ago my MIL got into an argument with my husband. In her usual way, she dramatically leaves the argument by saying something like "I can't take this any more, I need some distance from you" and refuses to further respond to my husband, even up to this day a month later. For context, the argument was about her saying some shitty things to my husband and him being reasonably upset about that and confronting her. She, as usual, made it all about herself (basically throwing out every possible excuse to avoid responsibility for her actions) and threw a fit. Then proclaimed she was going to "distance herself". (btw This isn't the type of argument my husband should just let go, she /does/ need to apologize and take responsibility for her wrongs here. plus she does this all the time and we are putting our feet down this time seriously)

After a week of "distance", I messaged her to ask if she was serious about wanting distance from us. My husband and I are so incredibly done with her attention seeking antics, we just wanted a clear answer so we know what we are dealing with. So I messaged her saying

a) asking if she meant what she said about wanting distance

b) if she did mean it, that's okay, but I need to know since we are having the baby soon (I'm currently almost 38 weeks) and having this type of thing be up in the air is very stressful for me

c) reminding her that distancing herself from my husband and I right when we are about to have a baby is a serious decision and can't be taken back later

She basically responded with "I never meant to cause you stress! I never meant to cause [husband] stress! I never wanted to be stressed or sick either. Of course I didn't mean that 💕💕💕 I'm always in your lives💕💕💕I'll respond to [husband's name] message soon"

So I responded that I was glad to hear that and that Id tell my husband. A couple weeks go by, no reply to him (she left him on read). So my husband messages her again, saying "Hey, you to told my wife you'd respond but it's been a while. are you going to respond?" and she sends a snarky reply like "I'll respond when I have the mental energy. I refuse to argue with either of you."

Mind you, this pissed me off BIG TIME because I was nothing but polite to her and have never once in my life attempted to argue with her, and because to top it all off she totally lied about not wanting distance. Leaving someone on read for WEEKS is distance. refusing to reply even after a month is distance. so I'm pissed she had the audacity to lie straight to me when I asked her such a straightforward question such as "Hey, did you mean that?" So after that we basically just chalked it up to "yeah, she lied. She wants distance. she wants to have her cake ( get her distance) and eat it too (not have us be mad about it) at our expense (ignoring my husbands completely valid feelings and ditching mid argument) and it's not happening."

I have made it very clear to her in the past that my husband and I are a team. She can't be in one of our lives without the other, especially considering the terrible way she's treated my husband. My husband has also made it very clear that she is not going to be allowed to flip flop in and out of our child's life, because she has a habit of doing that to us. she has to decide if she wants to be in or out and stick to it. over the last several years she has WAY too many times gone radio silent on us for months and just checked out of our lives with no care for how much that hurts my husband. Now having a baby, we will not allow her to dip in and out of their life too, because that's not healthy and I don't want my child to think they can't rely on someone who says they love them. we are a family and we stick together.

so, finally, the immediate problem I need advice on: today she messages me some bullshit like nothing is wrong between us and she has done nothing. I haven't "viewed" the message yet because I don't like to leave people on read. Do I have any obligation to reply to her? I want to just leave the message ureplied to, because like I said above we have made it clear in the past that she can't selectively choose when to be around and she can't act like nothing is wrong between us when she absolutely has shown she wants distance despite the fact that her first grand child is about to arrive. I'm not trying to be petty, trying to enforce a boundary we have set. Should I leave her message unread and unreplied until she grows up and responds to my husband?