My 4 year old won't share mummy

[Tenochtitlan]

My 4 year is very demanding at the moment and constantly shouts for my attention. I know this is not unusual at this age, but as I Have a 2 yr old to look out for too, it can be really difficult, and I can feel myself starting to lose it with him. For example, I was recently in a Playbarn with him and he demanded me all the time, constantly shrieking for me at top of his voice and grabbing my hands and top so I couldnt cross to other side of Playbarn to check 2 yr old ok. I've tried to explain it to him, saying we have to share mummy, but this is still carrying on. What is more, I'm starting to feel guilty now, as i am evidently getting irritated with him, and I literally had to prise him off my fingers the other day because I had to go and sort his little brother out (who was just about to make off with some kid's crisps). Anyone had/ having same experience or have any advice to share?

I feel your pain. Dd is 3.11 and has always been a complete mummy's girl. We have a ds now too, 14mo, and dd is pretty jealous of him and really struggling with it. I feel so sad for ds that anytime I try to give him attention or play with him it's to a sound track of 'play with meeee mummeeee, MY turn, how long are you going to play with him, mummmeeeEEE!' I'm so thankful for the mornings dd's at preschool. I love them both and hate feeling torn in two.
I can't give advice really as I obviously haven't cracked it. But when we're out somewhere like soft play, I explain that it's my job to keep both of them safe, ds is tiny and easily knocked over and so if dd wants to stay with me and him that's great, if she wants to go and enjoy the 'big girl' climbing that's great too. I worry about dd, she's obviously stressed and anxious and however much attention and one-to-one time I give her it's never enough. She's started bedwetting and waking at night again too.
I have to confess I'm not enjoying parenting much at the moment - I'm exhausted, burned out and have to work really hard not to loser temper with dd. I feel like a broken record going 'how do you ask nicely?' 'Use your friendly voice please' 'he's using it now, you need to wait your turn...'