Bipolar aunt ignores niece existence because of infertility

My husband and his sister have never had much of a relationship, she never calls or sees him unless at family dinners once or twice a year. The only time she calls is crying to him when she's had breakups or is feeling suicidal. One time she went missing and we all walked around on foot searching for her.

Fast forward my husband and I fall pregnant, we are overjoyed. We call everyone to let them know it's a girl. His sister squealed and seemed ecstatic congratulating us. Saying she was so happy to be an aunt.

Fast forward again I'm in hospital with medical complications in pregnancy, hypertension, gestational diabetes, preeclampsia. My livers deranged. I'm sick as a dog admitted for 3 weeks straight. Don't know if I'm going to die. Don't know if my baby will die. Baby is growth restricted, unusual dopplers, doctors say emergency C section she's coming out.

Zero phone calls. Zero messages the entire pregnany.

I didn't care at the time I had too much to deal with. Then she messages me on Facebook before surgery "if you need anything at all I'm here" "I can't wait to meet her" "I'm going to be the favourite auntie" "bobs kids (her bfs kids) can't wait to meet her too!)

After birth, my baby in NICU cause premie. Lots of scares.

Zero contact from her. Not even a phone call saying grats. Or asking how baby is. Nothing.

Fast forward my daughters first sleepover at 2 months old at her granmas, my husband's other sister flys up from another state to meet her niece. Taking time off work and forking out for plane tickets.

Whereas other aunt literally lives five minutes from us and

Srill no contact from absent aunt. The other aunt also got flu and covid shots etc so she could hold her niece.

It's been 5 months of no contact. Granma comments sometimes how she's talked to absent art on the phone "when are you going to meet her"

Says she always laughed it off apparently, "I'll see her at Christmas I won't need shots by then"

My daughter will be 8 months old by then

My husband has been hurt this whole time so has ceased contact. I talked to his mum, Granma one night about it.

"Do you know why she won't call or see her niece? I know she has fertility problems, do you know if that makes the idea of seeing her niece painful?"

Granma waved it off "no, it's nothing like that she's always been self absorbed. I don't hear from her for months, she wouldn't speak to me at all unless I didn't chase her and call her all the time."

I was like ok. And discussed how the lack of contact was hurting my hubby, how he was angry and disappointed because he was. Then I surprised myself by crying. Told her it was the false platitudes in hospital when I was at my most vulnerable "I can't wait to meet her" "if you need anything. And then no word. Nothing"

Granma said not to worry about it. So I let it go

Well then last night. Husbands sister calls him hysterical and in tears out of the blue. He can barely understand her. My stomach drops. Is she ok? Is she hurt? Has she hurt herself? I'm ready to drop everything and run.

Hubby walks off on phone attempting to console her. I don't know what's happening.

I call her mum (granma). Xx just called she's distressed and on the phone with Scott do you know what's going on is he ok?

Granma says not too sure she called me two seconds before I could barely understand her but she said something about needing to call (husband) and explain why she hasn't seen (mydaughersname). Then granma said tell (husband) to call me after he gets off the phone with her. I'm like ok

Husband gets off the phone, quickly calls granma then comes over to me.

"She was just calling to explain why she hasn't seen (our baby). It's because her and bf been trying to have a baby and are looking at ibf. She will have to use donor eggs. And she's been diagnosed with bipolar disorder."

Hubby then said "her unhappiness about us having our daughter doesn't detract from my happiness of having her. I'm not angry or annoyed but that doesn't mean I'm not still disappointed."

No one's asking how I feel. It's like I don't exist.

On one hand I'm doing my best to be empathetic. On the other hand, I wasn't acknowledged at all. Only my husband.

So ... what's some advice? How do I be a supportive sister in law? Can someone explain their experiences with bipolar disorder? How do I not hold a grudge?

Even if absent aunts in grief about fertility and has a disorder and is miserable about her own circumstances I'm not going to stop enjoying my daughter or celebrating her existence. Fuck that