AITAH for being upset my sister in law planned her wedding for the day before my husband's birthday

Lots of context She and her partner are already legally married and this is essentially just a very expensive party. She has a baby and has already had issues with infidelity in her relationship and less than two weeks ago she was even questioning if she wanted to stay with him as all. And they all (her, the baby and her husband) plan to move across the country at the end of summer. Their aunt yelled at me over the phone for being inconsiderate of the bride and her trying to 'move on with her life and get away from her past' (the bride never agreed with this and said the aunt took the phone after over hearing me on speaker). My husband and I are bride/groomsmen as well. Despite all of the craziness I've tried my best to be as supportive as I can even though I'm mostly just confused.

Nevertheless the wedding was initially supposed to be in June or July (I had been told this less than two weeks ago as well). However I'm really close with my sister in law and we plan things pretty regularly. This next month is my husband's birthday and we have been talking for 2-3 MONTHS about doing something for his birthday. Get a matching outfit with his niece for his first bday since she's been born.

I get a random message asking if he had the day before his birthday off which we had talked about over a month ago and already requested off. So I was like yeah and thought nothing of it because I assumed it was for his birthday like we talked about before. A few more days pass and I give space because of the issue with the aunt and not wanting to create any problems for anyone and I get a random e invite for the wedding. Honestly at first I didn't even open it because I had just been told by the bride it was going to be in June or July so again I don't think much of it.

The wedding is hour and a half away the day before his birthday. No call no mention of it at all. Just making sure he is off. No cancelling the previous plans or even concern he had other plans for his b day. And if it were a different situation, like they weren't already married and had a baby and it was like a time is of the essence kind of thing I would be so much more understanding but there wasn't any reason to move it forward and it really feels like my husband's first birthday with his baby niece just kinda got smashed to pieces and turned into her wedding. Also her anniversary will always be the day before his birthday and I was talking to my own sister and she thought that alone would be too weird. Everyone I've talked to has kinda said they would have at least discussed it with the person or wouldn't have done it at all because it seems inappropriate.

My husband has already been feeling abandoned because his sister is moving across the country and now he has the burn of feeling like no one cares about his birthday and it being overshadowed and cast aside for the wedding. We have been spending a lot of time and energy to make sure they are okay and worrying about them since they had their kid and it really feels like none of that is being reciprocate and if this was something they did to include my husband it would have been mentioned to him at the very least. It feels more like this is the date the venue had available on shorter notice and they didn't care how close it was to his birthday. I would never do anything similar to my sister which is why it is so hard to wrap my head around. Like if I heard the date was the day before and I was already married and had a kid I would be like well I don't have to do it on this day I can pick somewhere else or a later time if I need to. Hell even ignoring all of the context I still wouldn't do it because it's weird to have ur wedding that close to ur siblings b day. (At least to me).

My first gut reaction was to be angry about the whole thing but my second thought was what if I'm overreacting to the whole thing and kinda just want to see if this is kinda an unspoken rule that people just 'know' is a no-no or if I'm dramatic. And if I'm not dramatic what in the absolute heck am I supposed to do about this because if I address it at all I'm the one trying to make the wedding about her and her husband, but also I feel like if we just go and act as nothing is wrong and be the 'better' person it's like saying that level of disrespect towards my husband is alright and I don't want to come off as doormats. My husband and I have mentioned not going but that also sucks too because we still want to support her but I don't think it's unfair for us to want her to consider her brother when planning things especially one of the last big get together before she moves a plane ride away especially if that plan directly replaces his own birthday with her celebration.