i really wanna yell at him

yeah, it's ok to look at an expensive car, to get all into it, to get into the idea of buying a new car, even if it isn't the expensive one. and i've been supportive of that, i really know that i have. but i feel triggered by the fact that he's going to go test drive one. it's ok to do that, too, but it feels like one step closer. if he can swing a new car payment, why can't he go to therapy?
even though i have repeatedly acknowledged that therapy will not 'fix' our relationship, it will most likely improve things, and what i really need is for things to improve on my end. it can't only be my responsibility to prevent a conflict from escalating, and i do not deserve the blame and the anger being continually directed toward me. i would like for him to make an effort to change his behavior.
my therapist was mentioning that he may not be ready for therapy because he is so vulnerable when it comes to acknowledging his own faults. and, true, it does make him feel pretty horrible about himself when he feels that he is in the wrong. the right kind of therapy would indeed show him that allowing his emotions to control his behavior is in fact hurtful toward me, and it's possible that he knows this and is not ready to face it.
i'm not ready to make an ultimatum, and if there is a way to do this WITHOUT making an ultimatum, all the better. but i'm tired. and i'm scared of his volatility. i'm afraid that there will be more episodes where i feel very hurt. i am afraid of him telling me he's going to leave, yet again. i am afraid that he is going to say hurtful things. and feeling blamed--hearing blame--hurts me.