Why does my ex RANDOMLY keep calling me ? Wants me back ? Crazy ?

asked my bf of five months for a temporary break
i had tried to discuss with him how i feel like im a low priority
he said yes i am right now and he is so busy with $$$ work projects and his son during satrudays that perhaps i should start hanging out wiht my friends early saturday evenings and he can always meet me 9pm or later
that just sounded like he was trying to turn me from his exclusive gf into a booty call.
i explained how much he means ot me and how i want things to work
that was two weeks ago
he reaction was to be immature and delete our relationship off facebook.
since then he has called me 8-9 times
a few times were nice low key conversations, one call was late when he was acting jealous and horny for me and the other few times he got my voicemail
i wrote him a long impassioned letter 5 days ago.
i asked him if he wants to get back together and thats what i want
that i want to try and make it all or nothing.
he didnt write back
instead he called me at 8:30 pm saturday night but i was already out with friends and didnt get his voicemail until 10pm and by then he didnt call back because he was leaving for biz trip sunday morning
now last night he called me just to tell me he was enjoying himself at a special spa and that he was bathing in dead sea salts.
what the hell did he call me just to tell me that an dhang up ?

why does he keep calling ?
my most recent letter made it abundantly clear that I’m only interested in resuming a serious relationship.
Not a friendship, not a booty call deal.

he is turning 40 in two weeks and apparently is freaking out a bit.
perhaps i should wait until after his birthday to get back together or talk to him ?

thanks !

im a youngish 31 btw.
1 hour ago – 4 days left to answer.
Additional Details
he has a house , he is divorced, so at one point he was able to be mr stable.
i think i started dating him when he was his lowest ebb ever.
Had been financially wiped out.
So apparently when he started seizing new business opportunities he turned into a total workaholic.
I think is some ways he thought he was being very caring to tell me to have fun with my friends.
but he didnt se eit made me feel marginalized.
My friends think the fact that he is still acting upbeat and calling me AFTER I layed all the cards on the table and made it crystal clear I ONLY want a committed relationship is a very good sign.
They said a man after just some tail would’ve run screaming ….
perhaps they’re right …..
he did wait 2.5 months before we had sex. and when we started dating called it “our courtship”