Prufrock sorry if I'm repeating what others have said. I started to read the threads but I'm so tired I'm off to bed and don't have time to read the rest.
I've just turned into a SAHM. Ds is 2.2 and dd is 10 weeks now. I have to get out of the house each day or meet with friends as being alone all day makes it a long day for both of us. I wrote out the routine I wanted to follow but this is obviously flexible and has been since I wrote it. I have activities planned for ds each morning such as playgroup, singing at our library etc and then in the afternoon I have other activities which can be done at home such as learning the alphabet one day, number the next, colours and so on. Obviously the afternoon activities wouldn't take the whole afternoon so I have other things planned as well such as puzzles, painting, drawing, gluing, reading etc.
When ds was initially born and got a bit older I used to have the TV on a lot but I made a concious decision not to have it on when I became a SAHM so do in the mornings until 8.30 which gives me time to have a shower, get dressed and have breakfast in a relative idea of peace and quiet.
Since writing out the routine I find that there isn't actually enough time in the day for all the activities I have planned (afternoon ones that is) and am feeling guilty for not actually doing them.
I also wrote myself a routine for meals as I was becoming stumped when put on the spot as to what to feed him for lunch and us for dinner. I am quite an organised person so this has worked exceptionally well for me as I feel I have some focus/direction each day rather than just winging it.
Most days we tend to catch up with friends which gives him time to play and interact and me to have some adult time. Poor dd just tags along and sleeps when she can. I feel a bit guilty about not having a strong established routine for her but am not beating myself up about it too much.
Hope this helps and things get better.
Oh yeah, I also found I was getting really grumpy with ds at around 4.00pm but the routine has helped cure that and also the fact that each morning I wake up and tell myself that I'm going to go one day without yelling at him. I feel a bit like a member of AA or something but it works for both of us and we now have wonderful days together.
One last thing I found that by giving ds lots of notice of what was going to happen each day meant that he dealt with each activity really well. The night before I tell him what we're going to do the next day and that's why he needs to go to sleep and then in the morning I repeat all of the days activities including breakfast, lunch and sleep time and then as the day goes on remind him of what we have left to do. This has worked really well for us as now at sleep time he goes down really easily knowing he has lots to do when he wakes up and that he has to have a sleep first before we do any of it.
Good luck, chin up and tears are a great way to let out emotions so don't hold back.