Feel for all of you, I have a toddler who will be 3 in March and twin babies at 14 months. Toddler alternates between being really sweet with the babies and hitting them with toys, pushing them, etc when he gets bored or tired or frustrated. If I shout (which I am occasionally driven to do) he crumples into tears. If I remain calm he takes no notice and calls me grumpy (and worse).
I have a rotten temper and find the main thing is to stop myself reacting instantly to what has happened (not easy when the toddler has just pushed his sister over for the 10th time today).
I won't call these tips but this is how I get through:
I find it essential to get out every day ... even if only a short walk to the local shop for an "essential" item, whether we need it or not. Of the five days I'm alone, we go to a playgroup on one day, he has a day in nursery, we visit his Dad at work and have a cake once a week for an hour, that leaves me with two days "free" to fill with walks, visits to family/friends, etc.
He improves after a nap so I let him have one (his Dad is absent all day but gets him to bed in the evening so I figure he owes me that much!)
He loves books, so if things are going pear-shaped I sit them all down to read and that makes everyone calmer (including me)
If things are going really badly I take him up to his room where he has some special toys that his baby brother and sister are not allowed to have. I leave him on his own (which he's quite happy to be for a short while) for fifteen minutes to have a quiet play, then go up and have a chat when I am cool and he is happier.
To add to the volatile mix one of my twins has just started biting. The look on my toddlers face when the worm turns and he gets a nip is outraged ... like he thought he was going to be the only one handing it out and it never occured to him that he might be on the receiving end! Sigh ...