DH getting angry when his team loses

[Olinguita]

Today there is a certain important sporting event in which DH's country plays their greatest rival. DH's team is not currently doing well. Cue scowling face, yelling at the TV and general bad mood. I'm going out this afternoon with our one-year old but dreading the awful atmosphere I will come home to if his team doesn't win.
AIBU to think it's just sport and a grown man shouldn't create an unpleasant vibe at home over it?
He is dealing with some mental health issues at the moment and sadly has got form for really dark moods and quite nasty outbursts, so it's not a cut and dried case of an otherwise lovely and easy-going husband blowing off some steam at the weekend (in which case I would just see the funny side of it).

You can only excuse behaviour for 'mental health issues', I think, if he also recognises he has these. I hope you are not making the diagnosis, and therefore letting him get away with self-indulgent bad behaviour. If he has been diagnosed with mh issues, what is he doing to remedy them?

Dark moods are one thing. They do not usually go with nasty outbursts IMHO.
Aren't they opposite ends of the spectrum?
Is he really depressed or is he 'just' a rager?
So he shouts and rants.
Does he throw things?
Hit things?
If so, think hard about where you want to be and how you are allowing DH to teach your DS to behave and treat women.

Being miserable whilst watching it is one thing, but then continuing, together with the other outbursts, are not acceptable, from him or anyone else.

Did you not read the OP?

He is dealing with some mental health issues at the moment and sadly has got form for really dark moods and quite nasty outbursts, so it's not a cut and dried case of an otherwise lovely and easy-going husband blowing off some steam at the weekend