How long can I keep breast milk out. how can I store this?

Hey mommies I just had my son the a few day ago and I was hoping to breastfeed atleast for the first few months. I was due in 2 weeks but he came alil early and I'm really unprepared. we came from the hospital a few hours ago and I just expressed some milk, it was getting so hard to try to latch him on my nipples look all kinda of crazy. iv been given the "look" by nurses and even my boyfriend ! (who didn't even believe bf was important) when I was in pain and when I asked for some formula instead just to substitute for a break. I don't feel supportive like this shit is hard and my bf asks questions like "Why don't u just breastfeed him? he only needs to get it in his mouth. do it like how they told you" etc. with a attitude. they had to put DS in a imcubator n under lights because he had a high level of beliruben. the only reason why I'm continue to do it is because I know it will benefit my son. like I said I was unprepared and I don't really want to nurse on the breast for the rest of the night because my nipples are cracked and I have been crying in pain . I have been hand expressing like the nurse told me to and saving the milk in little bottles they gave me. my question is how long can I keep them out? can I store this in the fridge or will it go bad? I'll be using them the same day just hours part when son is hungry.. I won't have any of those baggies to freeze them in and we won't probably be able to get some til my bf gets paid in 2 weeks. /: