Selfish or not? Didn't help his ex out

Out of interest OP, how many times has your husband asked the step dad to help him out with stuff like this?

No, that doesn’t make him her son. ‘Stepparent’ is a title, and not one that obliges her in any way. Whether you personally approve or not, she isn’t his parent and she isn’t responsible for him.

I would have taken SS. He is, after all, your stepson and you owe him some care and responsibility. Your gym class does not take precedence over your duty to nurture one of your DC. I don't think you are selfish, I just don't think you see your DSS as your DS - but he is because you are married to his father.
You were not helping out your DH's ex here, you were doing what was needed for your DSS.

So all the help she’s previously given now counts for nothing?!

This. What a shit dad that his own son didn't tell him that the presentation was happening.

Says a lot about their relationship. Here's hoping it never happens to your child if you split up.

There may also be a time in the future when the OP and her husband want a one-off modification of whatever arrangements there are regarding the SS and the mother will remember this and not be co-operative.

Yes, she chose not to allow other people to dump their problems on her to solve. I’d call her an excellent role model.

I would get your DH to ask to be added to WhatsApp, email etc update so he can keep on top of it, not your circus and not your monkeys.

Happens all the time on here. Especially step mums!

It’s a title, that’s it. It doesn’t make her his parent, or responsible for him.

He’s got two parents to meet his needs, neither of which is OP.

I bet she’s got lots of family members she’s equally not responsible for, in law and biological. No, her stepchild is not automatically going to be her priority,

I never understand why some people think a stepparent is obliged to take responsibility for a stepchild, more so than the actual parents apparently, yet here we are.

Well it’s a shame the child missed out, these things mean a lot to kids. His mum should have given you all more notice, but the fact you put a PT session you do 3 times a week over a presentation for your SS doesn’t paint you in glory let’s face it.

He became her stepchild when she married her dad ffs!!

YABU, He is a child, he needed an adult you are his step mum.

I’m with you OP. This woman dicks you should regularly and you’ve helped out frequently in the past.

I would have taken him, I wouldn’t have the heart to say no knowing he’d miss a presentation, but I do think his mum and dad are pretty shitty not to have organised things better to ensure they could be around.

Fair point and I think it is unfair that you are being blamed.

The child missed out on his presentation because neither his mother, nor his father, could get their shit together enough to plan their day so that they could be there for their son.

That child needed his parents and they didn't show up.

YANBU OP, the ex could have easily paid for a taxi for her parents and her son to get to the event. Or could have asked on their football team's WhatsApp group if he could ride along with another parent.
Sounds like she's shit at planning and sorting out her life, sad for the poor boy but she did have other options and I fully understand why you declined to help. As PP said, is she also accusing her own partner of being selfish???

Considering dad and step-mum have the son for three days a week (so nearly half) it’s amazing that the dad didn’t get himself up to speed on his son’s activities.

Why didn’t his mums partner go?

I wouldn’t have gone either 🤷‍♀️. I get little time to myself like you inbetween toddlers and work. Mum can’t have been that arsed if she didn’t go herself or tell you or his dad about it

I wouldn’t give it anymore head space. Block her and tell your partner not to pass on her nasty comments. She’s the one who picked work over her own son 🤷‍♀️.

Personally I'd have taken him. I couldn't have let him miss it for a gym session.

I also wouldn't have got caught up at work a night I had plans with my child though. I would have been leaving on time! (That's probably easier for some than others though)

Why couldn't his maternal GPs, who he was already with, take him in a taxi? Why aren't they getting all the flak OP is getting? Sounds like OP steps up plenty for her DSS and ought to be allowed to have a life.

The child missed out because of his PARENTS and their poor planning.
OP helps out a lot from the sounds of it, it’s not reasonable to emotionally blackmail her into doing it EVERY TIME, especially when she’s not considered important enough to be invited to this thing in the first place.

As OP said, she wouldn't have booked the PT session (not gym class FFS) if her child had a presentation.

As others have said, this is on his parents for failing to communicate and plan. If he is with his father 3 nights a week, why isn't dad up to speed on the boy's schedule? That doesn't bode well for his involvement with OP's child.

Also, grandparents could have Ubered or taxid. Or, what about a lift from other parents whose kids are on the team?

There were many solutions other than prevailing on the OP. That said, if I liked the kid and could reschedule the PT, I may have considered taking him.