I have had two heart attacks, serious multiple comorbidities and constant nausea caused by medication. You really need to seek help, there are medications for this, it's just a matter of finding the right ones. It has taken me six months to resolve this bad period.
At one point recently I hadn't been out of the house for six weeks, due to nausea and vertigo. The most difficult part was losing my independence and not being allowed to drive.
On many occasions, I have been miserable, thinking this is what my life will be, then with support life got better.
I went to the supermarket today, had a nausea episode, but took medication for it, when I got home. I will rest until it passes.
There is light at the end of the tunnel, but you can't do it on your own, but you also need to decide that you will help yourself. Small steps at a time. Set small, achievable targets.
I"m surprised you don't appear to be on a cardiac rehab programme. Part of it is psychological counselling, which I reluctantly accepted. It changed my attitude enormously. I find that cardiologists are very blunt and don't mince their words, which doesn't help your mental and emotional health at all. Mine told me I would die of heart failure, due to my RA. He then walked away, without another word. Compared to my other kindly consultants that was hard to take.
I hope your situation improves and that you actively seek help.