Ooh, I've got here at the start of the pile-on on the OP, I always miss it! 🙄
Of course yanbu OP. As a (young) widow myself, despite the fact that I have decided that I will never remarry, of course I would expect my late husband to be mentioned in a wedding speech, as a mark of respect, and as a comfort to my children, I would be discombobulated, as I would expect my new husband to be, if an entire speech was dedicated to to him, and my new husband not mentioned. (I would also btw stop anyone in their tracks who referred to him as my ex husband, but if that was how I referred to him for some reason I couldn't take umbrage to anyone else who did).
Agree though that it is only courteous of the MOG to be presented with flowers, even if she did try to steal some glory and exaggerate her part in the organisation (but I would honestly roll my eyes at that part).
The dick move by the brothers would be halted quick smart by my friends before it became such an issue that the video of the dance was ruined, so I think I could also let that part go. I wouldn't even blame my DH for not stepping in really, because if the brothers are such dixks, then for him to do so may well have caused a chaotic scene which I certainly wouldn't have wanted (and I'm willing to bet your DH knew that only too well if their loutish behaviour is anything to go by).
MIL's comment to your father sounds mean spirited and nasty, so I'd be giving her a wide berth from now on, unless some sort of apology was forthcoming (which by the sounds of things isn't likely to happen), so she will have only herself to blame when she sees very little of me, far less of her son if he's a half decent husband, and equally as little of any grandchild(ren) who may arrive in the future. Children don't need to be involved with someone who shows that sort of negativity and disrespect to their mother. 🤷🏼♀️
And finally, PP are right, in that your dad should probably have put her in her place and kept that from you to save you any more upset. All in all though, unless all of the above was atrociously overboard, then it really is likely that it ruined the wedding far more for you than for your guests, while although still unfair on you, means that at least everyone else probably had a wonderful time and will hopefully remember your wedding fondly.
I hope your DH is on your side, comforts you over the whole shenanigans, and you have a wonderful happy life going forward with as little contact with his family as you desire.
Congratulations on your wedding OP 💐