accepting that TTC no. 2 may never happen

Frustrated today to the point of crying. I have a 1.5 yr old and my marriage broke down. I raise my boy alone now with the dad involved pretty much only financially. We make an effort to get on, I know he doesn't want to let go of us, but he broke my trust in a way that is just not easily restored. Maybe never. Being a lone parent is much harder than I expected. My boy is a gem but he obviously has needs that only male figure can meet. But a new man? Umm... Hard to imagine. I feel like I'm failing my son with my choices, I result in shouting at him in frustration and crying, at the end of the day I sit alone exhausted and cry my eyes out because it's like I do nothing but discipline and shout and correct. Parenting is obviously a two man job and I don't cope well having to respond to every single need, whiny demand or tantrum alone. To give my all I neglect most of my own needs and it made me burn out. In trying to give more I gave less. The dad doesn't cope with the boy alone but he adores him, I know that. And to make things worse my friend just had a baby and it made me want to have a girl so much! I really think if my boy had a sister he would learn to share more, especially attention. But seeing my situation it seems the most idiotic thing to crave right now. But I do, I so do. It's like the more I struggle the more I grieve because my dream of having 3 is melting before my very eyes. I just feel really bloody shit today. Sorry for the rant, I know many mums would be beyond grateful for just one.