I don't think people saying things like this necessarily comes from a selfish/toxic/controlling/possessive place. I think it often comes from a place of fear and inability to empathise with the depths of suffering needed to contemplate suicide. I think as humans we relate to other people's situations via our own experiences and life. If someone's never been suicidal, there's just no way for them to fully understand or empathise with it, it just doesn't make sense to them and no matter what we say it's unlikely they'll actually 'get it' completely. It's not because they're selfish or not trying, they just can't do it.
Sure, they could certainly respond better, I'm not denying that. But I think it's very natural to react from a place of fear when hearing a loved one express being suicidal, and this leads them to say things like this that just aren't helpful. Again, I don't think it's because they're trying to control us or whatever.. they're scared, they don't understand and because of this they feel powerless.
Maybe you could try gently explaining to your boyfriend how he could best be there for you - e.g. just listening, not offering solutions or saying things that make you feel more trapped or powerless?
Obviously you know your boyfriend and the situation better than anyone here, but perhaps don't automatically jump to him being selfish/controlling etc., I imagine a lot of people would say similar things initially, despite how unhelpful it is.
Despite all this, I totally get why it upset you - I'm sorry it felt like he didn't understand or care.