Im struggling to come to terms..

I was told I may never be able to have kids but anyways me and my boyfriend have been going amazing and all of a sudden yesterday was like I didn’t exist after I asked him if he wanted kids? There’s 8 years between us(I’m 20). I don’t know how I’m supposed to react like we didn’t start our relationship off the easy way but I thought this were going great with us. He always used to talk about getting married and what dress I would like and colour etc and even before we discussed kids names but now it’s like he doesn’t want to be with me!? I suffer with depression and I’ve been having a bad few days so I thought maybe that is why he’s being odd with me but he’s never been like it before.

Someone help me please before I have a massive meltdown🙌🏻