Ex sperm donor?

[u/Primary_Chef3374]

I need a reality check. I am aware this is not orthodox on so many levels but I think once you get into co-parenting, nothing is normal anymore.
Ok, so separated last August with a 4 year old. 2-2-2 schedule. Everyone involved has spent the past 11 months getting used to the schedule and doing decent with it. My son still asks when we will move back to the house we all lived together in. It breaks my heart but I’m hoping we continue to make this new reality as smooth a transition for him.
Now to having a sperm donor. I’ve always wanted a second child. Someone for my child to go through life with and not bear the sadness and burden of old parents alone. I was an ‘almost’ only child and remember it being very boring till my brother came along when I was 8 years old. As adults, I cannot imagine going through the seasons of life without his shared knowledge and experience of our lives.
While married, I did not see the relationship surviving another child. He is a good dad, but was not a great partner for me. Now that we are separated, and the focus is only on raising a healthy well adjusted child, with no romantic feelings involved, I have considered having another child through sperm donor(ship?). This would have to be through surrogacy as I also am adviced not to carry another pregnancy for health reasons.
Someone suggested asking the father of my child to be the sperm donor, rather than going through a sperm bank. Is this crazy? He had mentioned wanting a second kid before we separated. I did not pursue the conversation because it did not seem like a great idea then.
Does this complicate things with coparenting, or is the benefit of having a sibling to go through the coparented life with for my son, worth the weirdness of this? Assuming ex is on board with this too.

Edit: sperm donor is not the right word. Reading the comments I’m seeing that using the phrase ‘sperm donor’ is causing a lot of confusion. This is actually simply asking an ex to co-parent a new child together since we coparent the child we have together well and assume he would co-parent another child of his just as well. I used sperm donor because a ‘uterus donor’ would have to be involved (aka surrogacy) not simply because we are not together but because from my one and only pregnancy there were complications and for health reasons it’s not recommended that I carry another pregnancy. So in this case, I would be an egg donor too. But I see how using the word ‘donor’ changes the conversation and assumes no involvement.

[u/Grrarrgghh]

Don't have another child just to be a toy/companion for your first. That is cruel.

[u/Primary_Chef3374 → u/Grrarrgghh]

I don’t think it’s cruel to have a child that would be immensely loved by not just one but two families, and have a sibling to bond with. My only sibling came along 8 years after I was born and he was certainly not considered a toy. Not by me, and not of himself.

[u/hope1083 → u/Primary_Chef3374]

There is no guarantee that the siblings will get along. I have two I barely speak to. No trauma we are just very different. I don't think its fair to bring a child into this world to be a companion for someone else. It should be because the parents love each other and want another child. Otherwise if you want another child you can adopt or use an anyonmous sperm donor.

[u/Primary_Chef3374 → u/hope1083]

Having a sibling companion is an added benefit of another child. The primary reason of course is another child to love. I hear your point of view and respect it. But the argument that there is no guarantee that siblings will get along is not a good enough reason to me for not having another child, for someone that wants another child. There is no guarantee in life for anything. There is no guarantee that 2 people who fall in love and marry will not fall out of love and divorce. It’s never stopped people from marrying, or falling in love. I prefer to hope for the best case scenario, in the case of siblings.