Hi again, there are some great replies here
I have just had another little boy (he is 4 months already!) and Ds1 was 4 just before the baby arrived.
I found it very very hard, particularly as a single parent. I was close to Ds1 before but also we have had struggles over the years - he has seen me quite depressed, which just means I'm a bit serious or preoccupied and also a bit vulnerable sometimes, so his behaviour will get to me when really he's just being a little boy.
When I got pregnant I was quite ill for a few months, which rocked his world - it wasn't easy as the second father left us/I didn't let him come back, as he was very strange/cruel etc. (long story!)
So Ds1 had a lot to deal with. My parents have always been there for him and that helped.
Anyway I had the baby and for a few days, Mum stayed around - ds1 was so angry and upset he could not even look at me. He was floored. I couldn't get out of bed for a while but actually after a week or so I was up and about, which helped a lot (if I am ever ill, it terrifies him, so that was the main thing) but even so he spent a few days being very angry and shouty. One night he just started to cry, and the tears poured out - I held him, it was so hard for him, suddenly everything was different. He was better after that.
We were all in the one big bed, and at first he used to find the baby's noise upsetting, but after a while he learnt to sleep through it - I would take Ds2 downstairs of he was noisy in the night, luckily it wasn't often - good baby!!
(This is quite a raw account of our first months, hope it helps though)
Ds1 would be vaguely aggressive to Ds2 for a few weeks. I made it clear that I knew he hated the baby but I wasn't going to let him hurt the baby, just like I would never let anyone hurt him, because I had two children I loved now, and they were very precious to me.
We had some hard days but suddenly he started to want to hold and hug his little brother - it was wonderful to see them ganging up on me, I would make a big joke about the baby grabbing my hair or 'headbutting' me, and pretend to shriek, which Ds1 loved and thought was hilarious - also a trick was to go and sit in Ds1's room and watch him play, and talk to the baby about Ds1 and how clever he was. That always brought a little smile to Ds1's face.
All this time, Grandma was Ds1's special person, while I paid attention to Ds2. It was hard to juggle at times.
I felt resentful of Ds1 for stopping me being happy around Ds2 sometimes, because he was being awkward or whatever. I also resented ds2 a little, or really was angry with myself, as I felt I had betrayed Ds1 big time.
However with both of them constantly around there was nothing else to do but all get used to each other, and at 4 months, things are going well - Ds1 no longer aggressive, though he has started school and is cross about that! he really loves his brother now, no doubt. And they each have an ally. Ds2 adores Ds1.
I went througha stage of feeling I had no love left for Ds1, but it was more like no energy as obviously you get tired in the first weeks. I cried a lot, we all did, except Ds2!!!
But I would never go back now. I couldn't.
I hope some of this helps a little bit xx