I agree. 1) She is cheating on you emotionally. This is probably the reason why you two argue so much. 2) She should be supporting you whether she agrees or not 3) take the job 4) demand that she stop talking to her... there is no need for it no matter how platonic it may be. 5) ultimatums are never good unless they are absolutley necessary and you go through with them ( like if you ever put a hand on me I will call the police and leave you, etc)

I have stayed away from the talking to the ex issue, but when anyone outside your own home commands more attention than me... YOU, Everyone will know I... I mean You again, ain't happy!

There is no way you talk to someone about your problems, or anything else without keeping me in the loop, and I don't care if its innocent or not, at least reassure me.