OK op am confused here, you have loved him since you were 8 yrs old now 60,
Anyway sounds like your partner is under a lot of pressure looking after son , unfortunately this isn't going to change for him, his responsibility is to his son, but he does need to communicate better with you rather than getting frustrated with sed situations with son, he may need to have clear boundaries with xw on days he has son, to which am sure he will deal with sons behaviour and not expect xw to come running,
You need to talk this through with him so you know moving forwards, he hasn't contacted you this morning maybe because he is feeling overwhelmed with situation with son, again not your fault but he does need to communicate better you and xw, put some boundaries in,
Wasn't sure if you both are living together, and son stays over, or visits, as you mentioned cooking for him,
Hope you can resolve this,