My recommendation is to take it slowly. Maybe find out if you can volunteer at a barn near your mom's mucking out stalls, grooming, helping with lessons, that sort of thing. If you start doing that, you might A) find out if you are feeling up to having another horse and B) make some important connections.
After/instead of that, try leasing! A lot of barns have horses that don't get ridden enough or that are available for quarter, half, or full lease. It is less expensive than owning and if it ends up being too much emotionally, then you can stop.
Finally, maybe you would be interested in working with a rescue horse. If you are feeling lost and purposeless, that might be very helpful. You should be careful though, since rescues can have serious problems. It should be under the eye of an experienced trainer, and you should never ride without someone close by in case something goes wrong.