When I talk about suicide to a pro-lifer, I don't go in with the intent to change their mind. In my cases, they sometimes can't stop imposing their moral values on to me. Most pro-lifers I met are psychologists.
They view themselves as helping me are fixing me to be less negative, a reason why I dislike Cognitive Behavioral Therapy in the first place. I don't agree with the stance they take as my thoughts being irrational, after all, they are my beliefs and the reality as I perceive it.
That's the hardest part about debating with a pro-lifer, they see that suicide is something that they will never do. And so they think that you should not CTB too. The problem is that their statements can not possibly apply to every case, the "it gets better" and "life is worth living" are examples of this.
I tend to tell them my pain and how it is chronic and I see no other escape than death. That the pain never goes away, instead I just learn to cope with it. That what makes me want to ctb is not just my thoughts of self hated, but the world itself. The day when all the problems on Earth are solved is the day I see life as bearable. Obviously they don't take that information very well, but I at least hope it will get them reflecting a bit. I tell them it's fine to disagree, but not okay to try to force something onto others.
(By their logic, they will eventually stop feeling grief from suicides because the pain is temporary and it will all get better. Obviously it doesn't Work like that.)