I’m so sorry to read of yours (and others’) heartbreak[s]. Lots of hugs to everyone.
Grief has no time line. Do not take any one else’s council on what is an appropriate time to grieve.
For the record, I still mourn and miss my gelding that passed away in 2012. He was very special to me. I love all horses, have ridden so many from so many different backgrounds, but he was special - not to anyone else, but to me. I think I was his person, and he was my horse. It was not an immediately wonderful relationship either and our beginning was astronomically hard as he was a brilliant athlete but had some physical complaints it took us time to cure; it was years on years of trying, failing, picking myself up from the dust, fixing, trying again - but in the end I had such a wonderful partner. There is one song that always reminded me of him (Keepsake, by State Radio) even before his death – and I get very sentimental (those that know me, know I am not sentimental type) any time I listen to that song, see an old bridle of his, or think of him. I still occasionally look for his bright face hanging over the stall window.
Habit, I guess.
I have let go of two other horses I loved dearly too (including my first OTTB/childhood horse, who was PTS last July) their loss was profound, but it was not as traumatic; maybe because for both of them it was their time to go, but with my other gelding it was so abrupt and ugly and awful. Certainly, the circumstances surrounding their death will impact how you cope; there are some where it is easy to let them slip quietly with their nobility still intact - and others where it is very hard; neither is a measure of your love or depth of relationship with them, but simply context that might change how you handle their passing.
Grief is blunt, visceral trauma. It takes time to heal. Be kind to yourself, think fondly of them often, and if you need to, talk to someone to help you cope.