Reading a string

I am currently trying to write a custom workflow that reads text data files stored in a CRM record notes section. These files have multiple lines of data and I need to be able to step through the 'file' line by line by line. I have thus far managed to extract the file contents ( including CRLF's ) to a string ( content ). How can I read the 'string' as a file. I know the line length is a constant 91 bytes in length. I have written the content string directly to a txt file and it is perfectly formed, but I'm trying to avoid creating a file on disc just so I can read it with file reader. Is there a way I can read this string ie 91 bytes at a time without writing it to disc first ?

My code so far

Protected Overrides Sub Execute(Executioncontext As CodeActivityContext)
Try
Dim context As IWorkflowContext = Executioncontext.GetExtension(Of IWorkflowContext)()
Dim serviceFactory As IOrganizationServiceFactory = Executioncontext.GetExtension(Of IOrganizationServiceFactory)()
Dim service As IOrganizationService = serviceFactory.CreateOrganizationService(context.UserId)

Dim Notes As QueryExpression = New QueryExpression With {
.EntityName = "annotation",
.ColumnSet = New ColumnSet("filename", "subject", "annotationid", "documentbody", "filename")
}
Notes.Criteria.AddCondition("objectid", ConditionOperator.Equal, context.PrimaryEntityId.ToString)
Dim NotesRetrieve As EntityCollection = service.RetrieveMultiple(Notes)

If NotesRetrieve IsNot Nothing AndAlso NotesRetrieve.Entities.Count > 0 Then

If True Then
Dim fil As Byte() = Convert.FromBase64String(NotesRetrieve.Entities(0).Attributes("documentbody").ToString())
Dim content As String = System.Text.Encoding.UTF8.GetString(fil)

' read the string and process to the relevant entities


End If
End If
Catch ex As Exception
WriteToErrorLog(ex.Message.ToString)
End Try