I agree about picking a partner like my mum - I always say this! It’s the whole, they can have feelings and get emotional or annoyed but my feelings (when like this) aren’t valid to them? As I’ve gotten older I’ve questioned if I’m like they say I am (dramatic) or whether someone else would react like me to this dynamic.
I think you've nailed it right here.
Your mum said to you "Both of them are ignoring you", and that made you feel uncomfortable for two reasons - 1. your DH didn't pick up on this fact and say "Oh sorry, I was a bit wrapped up in what I was doing" and come over and join you, which is what you might expect a normal, empathetic person to do and 2. your mum made this unkind observation with a sense of glee, which you would not expect a normal, empathetic person to do, particularly your mum!
So you're right, you're not off. Both of them are off. And then when you were understandably upset by their offhand treatment of you and did quite a sensible thing by removing yourself from their company (distancing yourself... not really dramatic unless there was a lot of loud huffing and banging things as you went), you're told off by your mum for 'making her uncomfortable'.
This is particularly interesting as the reason she was uncomfortable would have been that deep inside, she knew you went away because she hurt your feelings. But she doesn't want to admit that to you (or possibly even herself), so instead she directs the uncomfortable feeling she's having (caused by her own mean behaviour) outwards, towards you, by blaming you for 'making her' feel that way.... without reflecting on the fact that she had just made YOU uncomfortable first.
Now, if your mum and DH have a tendency to treat you poorly and ignore your feelings, nothing will change as long as you ignore THEIR behaviour. You need to speak up and call it out by expressing your feelings.
The way to do it not to have a go at them... like saying sarcastically "Oh THANKS GUYS FOR TOTALLY IGNORING ME, GUESS I'LL JUST GO AWAY THEN" or bursting into tears and saying "WHY DO YOU GUYS IGNORE ME ALL THE TIME" because that would be dramatic.
Instead, a different way to handle it might have been to take a breath and say in a calm voice, "DH, I don't enjoy being ignored until you decide you're ready to do bedtime. So please do it when you're ready. Mum, you sounded a bit gleeful when you pointed out I was being ignored, which is something I could see quite well for myself, and I find that hurtful."
Your mum may well have told you that you were being dramatic or making a big deal out of nothing, she didn't have a mean tone etc, in which case the thing to do would be trust your own perception, remember that you can't make her care about your feelings if she doesn't want to and stick to your own truth. "Well, my perspective is different but I see that you don't want to consider that. I'm going to take some time by myself."
If she then has a go at you for 'making her uncomfortable', by leaving, you could say, "I'm sorry you feel uncomfortable. I also feel uncomfortable with how you behaved towards me and how you then disregarded how I felt. So I think some space is best."
Obviously the same exact situation won't come up again, but you can see in the alternative scenario how you 1. speak up honestly and bravely about your feelings, 2. don't doubt your own experience because someone shows you that they don't care much for your feelings or tries to shift the focus onto you by telling you that you're being some way that you're not (dramatic), and 3. behave respectfully towards others (not lowering yourself to their standards) while standing up for yourself.