I’m so sorry for your loss. Toby sounds like he was a lovely guy, and while you were lucky to be his person - he was lucky to be your horse, too.
When I lost my gelding quite unexpectedly (there was no emotional preparation for it)… going back to the barn felt like I was suffocating. I asked my mother to help me pack up his things. I took everything I “needed” to take (tack, blankets, wraps, brushes, etc) but then you may find you have a bunch of “not worth saving, but shouldn’t throw away” items. With BO’s permission, I made a box full of these items labeled “FOR FREE”. fly spray, thrush treatments, poultice, liniment, etc - these things found new homes with people who would use them.
But I’ll be honest with you - it sucked. The people you come across who know, will be nothing but compassionate with you. But I didn’t want to deal with that. I could barely keep my own grief together, I didn’t want other people expressing grief at me (even though in most instances, it was for my sake, their empathy for my loss). My mom and I went when the barn was mostly empty (BO and my instructor).
Everyone’s grief travels differently. You may find that you can manage it as a carry-on for a while before suddenly, it becomes too heavy and you need to check the bag it’s in. For some people, it’s the opposite. For me… the hole in my heart has never gotten smaller. It’s been years, and I still feel his loss as acutely as ever. The only thing I can say is that in the years that have passed, while the hole in my heart hasn’t gotten smaller or filled up - my heart has grown larger. It took time, but it had to grow larger to fit all the love I have for my current horse. She doesn’t fill the hole he left, but she’s shown me a new love that needed new real estate in my heart.
But that took time. And I hope you give yourself time, whatever time it is you need. If being around horses helps you, spend time with them: my instructor needed “help” keeping her guy exercised (during spontaneous trips she took) and would need “help” keeping clients’ horses in work (…and they were always the same 2 horses who belonged to my friends… who, I think, arranged for her to offer me the ride but under this pretext so I didn’t have to navigate their sympathy). It took me time to go back though. It was difficult. Being in different barns with no memories was easier for me, going back to “my” barn was so, so hard. But test and see what feels right for you. Your heart may need something that someone else didn’t, and what worked for someone else here may not be a fit for you.
All of this said… no time we have with our horses would ever be enough. I’m glad you had the years you did with Toby, but I’m sorry that you didn’t have more. For all they will never be enough - I am sure they were more than enough to help teach you lessons and shape you as a person. My sincere condolences for your loss.