DANISE,
When I've been through times of great grief, such as following my father's passing, I too would find that it would sometimes seem to come out of nowhere and hit me like a ton of bricks. Then, too, there were the times when anything having to do with him would stir it up.
One of the boxes'o'stuff that I haven't yet gone through is family stuff. It's been thirteen years since his passing and it still stirs up a certain amount of grief.
For me, the biggest help was finally settling the estate. As long as the estate was unsettled I had it on my mind, and every time I worked on it it stirred things up again. Once that was done, it was as if a black cloud had suddenly cleared.
It WILL get easier. I have no doubt all your painting has been good therapy for you. I do suggest you do something FUN--if not a musical, then something else. The photography class, perhaps. Focus on the future as you put aside the past.
My best to you.