Of course you didn't. OP I am so sorry for the people who cannot understand that no matter the loss he suffered, yours was greater and you had no obligation to spearhead any attempts to contact and include your stbx in this process. Through your comments he has shown a remarkable lack of consideration of you and the little one by trying to include nonfamily in this process. Even as the other woman, I would be mortified at the suggestion of attending appointments or a funeral. It is not because of love it is because of lack of empathy. Your partner had options and chose to leave instead of filing for divorce immedietly, speaking to you frankly, being mature and considering he may be escaping his issues through other people. I see no mention of counselling, self reflection, or any sort of bonding with you other than an explanation that he fell out of love.
Love takes work and grass is green where you water it. People lose feelings but he could lose feelings and handle that befire jumping ship to someone new, a sign that he isn't grieving the relationship but escaping problems by seeking someone new.
You cannot seek escape and expect the people you leave behind to give you consideration in their times of hardship, especially if you added to it. Think of estranged parents: they are not entitled to a relationship on principle of family. The spouses of their estranged children are not obligated to inform the parents of their passing. He lost father privileges when he chose to act in bad faith without any proper planning. He had a choice to be family and he chased a new relationship and forced that prioritization over everything.
A man who tries to bring an affair partner to your appointments while pregnant is not asking to see his childs face only because of grief but because of anger and entitlement. Whatever grief is there has a shadow cast over it that he chose to be angrier about the childs face than horrified that you were handling this more on your own. Even if you had company, you heard the news and had to grieve. I would be so ashamed of myself if I were him. Even if the romantic love died, I shame him for losing the love of his fellow person enough to behave so inappropriately towards someone he spent life with.
Please be gentle with yourself OP.