I'm sorry you're going through this but both you and your boyfriend had to know it was possible to get pregnant again if you were using no protection.
I understand that birth control can fail, condoms can break and birth control pills are not 100%. If you use both faithfully they are pretty much so 100% effective.
Both of you are doing a great job taking care of yourselves and your baby. Be very proud of yourself and your boyfriend for doing that.
Having two children at 18 is going to be so hard. I'm sure you already know this. It will become a reality once your second baby gets here.
You CAN do this though. Both of you are working and as long as you can continue to work through most of your pregnancy you should be fine as far as enough money. If you sign the new baby up for daycare scholarship that's another thing that won't be coming out of your pockets.
No one can tell you what you should or should not do. I do think the best thing is for you and your boyfriend to calmly sit down and go over everything. It's understandable that he's upset right now. The two of you had plans and now they're going to change. There will be a lot more responsibility with having two children. Like I said though, if you stay strong this can be done and things will work out how you want them to.
I'm sending you a message.