I hate seeing you in despair like this.Please don't let that pondlife win by their views on this.It sounds very much to me from what you have said about her life before she was with you that by blaming you they are trying to get rid of their own guilt about their part in her life.Being so down and already blaming yourself they have made it worse by doing that.
You havnt said exactly what happened and I know it may cause you too much pain to do so,but it seems to me who is always drawn to the sea,that as an adult,if I go in there then no one is to blame if something goes wrong unless they physically hurt me.I once watched a friend jump in and the shock of the cold caused him a heart episode.He got himself to the beach but in the water i could not have got too him quickly enough even from shouting distance.The water was calm,there were others of the group in there too,no way could we have forseen it,so if the outcome had been serious we would not have been to blame, but we may have believed we were because grief bends our minds so cruelly. Do you think she would blame you or be really upset to know how you are blaming yourself.
My personal belief is that we have a spirit or soul which leaves when we die not staying with our body,not in a grave or our ashes. Taking it from a scientific point of view,all of us are made of and by energy.When our body is too damaged to repair it no longer needs energy so there is no energy in us.But all energy transfers to other forms.We can't see energy only its effects but it is never lost from the world,and so it makes sense to me that what we call our soul or spirit,or consciousness, the thing that makes us more than just a body is made up of that energy and can exist outside our body.Consciousness is what makes us aware of our desires but that is triggerd by reactions tied up in that energy.The things that brought us together,genes or chemicals that created attraction and bonds between us remain.So even though we draw comfort from having Ashes we don't need them for their energy to be around us.
Please take all the help you can get,but also please remember that even though you think you don't have friends,you made some new ones the instant you made your first post here.