Honestly man, beating a dead horse about this isn’t necessary. YOU FUCKED UP BAD. But it’s not the end of yours or Becky’s world if you choose for it not to be. Biggest recommendation, i would give Becky some time and space before formally and politely apologizing and admitting to what you did being terrible and reassuring her that you support whatever decision she comes to make. Next big step is to go seek help from a counselor or therapist and break this along with all your other problems you may be having down with them (THIS IS KEY). At the end of the day your relationship with Becky very well be over but only time and recovery between your individual selves can be the determining factors for that.