Struggling currently and feel at my wit's end

[B5670]

Am mid 40s and have noticed a huge surge in what I think is obsessive anxiety.
The anxiety is all encompassing and makes me feel like I am losing my mind.
My latest obsession is that my partner is talking to other women online and is seeing someone. There is zero evidence to suggest this btw but the slightest thing makes me obsess.
Can be an innocent communication with a customer that leads me to ruminate on it.
I am unable to focus on anything else at the moment.
It appears to be worse around the few days before my period.
Can anyone relate? Otherwise I am a totally normal person...I am extremely embarrassed to be in this situation.
Thanks in advance

I developed this last month, putting it down to a bit of peri-menopause and lockdown.

I told my husband exactly how I felt, he was concerned and confused.

On the flip side we were really horny as well. Last month I was sad and paranoid for about a week but gradually came out of the fug, this month it lasted a few days.

Thanks for answering.
I have not shared with my partner as i think it would freak him out. How did you cope with it?