onwardsmummy - sorry your feeling so low but I have to say I am happy you have posted this as I am going through something similar with DD (will be 14months in a few days).
It is now even harder as we have DS who is just over 3 weeks old. I am spending as much time with DD as possible so as she doesn't feel left out or pushed aside. ATM DS is still sleeping a lot and so it's normally just a feed and nappy change he needs.
I'm trying to get out everyday with them as I think I would be totally frazzled come 5 o'clock if I didn't. It can seem like a bit of a chore at times between getting us all ready, packing nappies/spare clothes for DS/food/milk/toys, fitting everything into the double buggy, getting them both strapped in and then actually getting out (we live in top floor flat!) but it is doing me the world of good.
DD really likes crayons, drawing on paper/toys/laminate floor! She is full of energy and very rarely takes breaks, not sure if your DS is the same? Agree with another poster about playing with water. We discovered this recently. I'll fill some pots with water, put some towels on the floor and let her play away (have to sit next to her though as she sometimes tries to tip the pots!). She'll throw some of her plastic toys in, her little ducks from the bath, she loves it - we both end up pretty wet mind you but it keeps her happy and entertained for 20-30mins. I built a den the other day but she didn't even bat an eyelid at it! She likes the balcony but really prefers to walk in and out of the balcony doors rather than sit and play outside . Do you have a garden? Could you get him outside to run around a bit?
From reading the other posts it's encouraing to know that it gets easier. DD gets very frustrated when we don't know what she wants. So once she learns more words hopefully things will be less confusing! She likes to point to things that she wants and when we don't give her it she takes a tantrum. We have started ignoring this and she stops quite quickly.
She absolutely loves Special Agent Oso (not sure if you have heard of it, its a cartoon on Playhouse Disney), its the only thing she will actually sit and watch so occasionally when she is frustrated and in a bit of a strop and I myself am feeling quite frustrated and helpless then I will put an episode of this on (thank goodness for sky plus, I always have a couple recorded to play in times of need!).
Sorry if I have been banging on about my situation too much . It's just good to know that I'm not alone!
I was recently looking on the internet trying to find different things I could do with DD and made a wee list, I've copied and pasted it below;
Reading
Puzzles
Building Forts and then bringing in the dollies, doggie, etc. to play too ... and eating in the fort
Sensory exploration stuff (playing with rice, cornstarch & flour, lots of MESSY stuff that is fun)
Drawing
Ripping out everything from every cupboard and drawer
Doing laundry (or undoing it, as the case may be)
Dancing/singing to music
Playing with the doggie
Jumping on the bed
Blocks
Playing with a ball
Tumbling and climbing on the couch ... taking the cushions off and rolling/jumping on them
Going out on her trike
Rearranging the fridge contents
baths (more for fun than getting clean)
helping Mum bake (stirring, measuring, etc)
looking at photos (albums are good, but DD loves looking through boxes of old photos: seeing Mama and Dada; 'sorting' them)
sorting through old greeting cards
emptying the recycle bin
dizzy lizzies
water games
play with playing cards
I gave DD one of our photo albums a couple of weeks ago, it has pics of her from about 6months ago along with family members, she really enjoyed looking through it and seemed to keep her entertained for a bit.
I really hope some of the above can be of use to you and that you start to find things a bit easier soon
Health Visitor was up to see DS the other day and said that although people say 'the terrible two's' it doesn't actually start at two......nobody mentioned that before