9 yrs older - could be to exert superiority over younger partner?
Expressed considerable offence at the suggestion - not open to communicating, listening, considering your opinion and feelings
Acting as though I am slow and obtuse when not grasping what he is saying in his incomprehensible texts …. he rang me with a sort of exasperated attitude, speaking very loudly and slowly and with a lot of an emphasis, saying what he was apparently saying in the texts - acting superior, belittling you and your intelligence
His elder sister is a teacher, there is quite a large age gap between them, I don't know what their relationship was like growing up, but they are estranged now - can't keep up a relationship with those closest to him
When I asked about him learning to use a PC/tablet/smart phone, he said that local men he talks to only really use the internet for online dating (they boast about!their conquests) and for porn use - That's an excuse. A convenient way to bat away advice to use the thing he's terrified of - computers, tech, reading.
I used to train employability way back, and some of the 50+ men were utterly lost. Dyslexia/literacy was often an issue, but also they were of a generation where they did woodwork and metalwork while the girls did typing and cooking at school. So when computers first came in, they found themselves doubly at the bottom of the pile.
At the root of all this is fear, and shame. Plus lack of emotional intelligence or the confidence to self develop. It's armour.
I'm imagining a little boy with siblings he didn't really know, feeling lost at school with no help, I'm wondering about his father, and probably that belittling attitude was something he learned from them all.
There must surely be some redeeming features?
Can he change? Does he want to / intend to
Do you want to put up with this any longer?
Here's what I'd do if I were you. Think through everything you want to say. Begin by telling him you love him and want to keep your relationship (if you do …), and you need to speak about something important and be listened to calmly and quietly, for him to hear you out. This is what you need for the relationship to continue.
I imagine you've researched literacy courses and tutoring options?
If he can't or won't respect that and allow himself to be more open, I'd be considering whether I'd want to be around that any more.