What an extraordinarily unhelpful and unkind response. The OP is a real person who is clearly distressed, exhausted and trying to manage three very young children in an unfamiliar environment, including an autistic child who needs extremely close supervision. Speaking about her in the third person as though she is some baffling cautionary tale, rather than somebody who is right here asking for support, is incredibly rude.
You have no idea what her relationship has been like, how gradually unhealthy patterns may have developed, or how difficult it is to care for an autistic child alongside a toddler and a baby. Nor does having several children somehow make her responsible for her partner choosing to disappear for twelve hours and leave her stranded without support. She does not need to justify the number of children she has or prove that she is capable of parenting them.
I don’t know whether writing comments like this makes people feel superior or reassures them that something similar could never happen to them, but there is a real and very upset person on the other side of the screen. Words can land heavily, particularly when somebody is frightened, overwhelmed and already questioning herself. A little humanity costs nothing.
OP, having read your updates, I think going home is entirely understandable. You have acknowledged that throwing the swim hat was wrong, but that does not make disappearing for twelve hours, failing to check on the children and then refusing to recognise any problem with that behaviour a reasonable response.
This also does not sound like one dreadful argument caused entirely by exhaustion. You have described a repeated cycle of him withdrawing for days whenever he is angry, while you are left to manage the children and wait for him to decide he is ready to speak again. That is not a healthy or sustainable way to resolve conflict.
For now, concentrate only on getting yourself and the children home as safely and calmly as possible. Ask the hotel and airport staff for practical help. You do not have to be embarrassed if you cry. You are dealing with an enormously stressful situation, and asking for help is sensible, not weak.
You also do not need to make yourself stay in Spain simply to prove that you can manage all three children alone. Of course you can care for your children. That is completely different from being unexpectedly abandoned in an unfamiliar hotel without the equipment, transport or arrangements you would have chosen had you known you would be parenting alone.
Once you are home, give yourself time and support before trying to settle every aspect of the relationship. Let somebody you trust know what has happened. Keep communication with him calm and practical for the moment, particularly around the children and where each of you will stay. You do not have to minimise what happened, but neither do you have to resolve your entire future while exhausted and travelling.
You sound heartbroken as well as angry, and I am sorry. Go gently with yourself. Getting everyone safely home is enough. (I have an autistic son too x).