Hello Carly
Sorry to hear you are feeling bad . I think you need to really look over the relationship and this, is this really what you want ? The guy became alcohol dependent ( that is no joke , I’ve bee with an addict ).

Perhaps you are taking too much blame for the demise of the relationship

I havn’t had a long relationship like you , but I have felt like you and honestly contact with my ex really screwed me up .

Feelings of depression etc are natural , but suicide is not a good thought. Therapy may help .
Take care