Hmm, HE has said you can stay in the house until baby arrives. That's just HIM saying that.
i would be interested in what a LAWYER would have to say about this issue. How long you can LEGALLY stay in that house.

$15 won't even cover dog food, from what i hear, it's expensive to pay for looking after pets, i think you need that $15 to pay for your own food, i would be contacting RSPCA about those dogs - think of your own survival first.

i suspect CL will tell you to contact local charities in the first instance. Once you are on CL payments, you might be able to get an interest free CL loan of a few hundred dollars, but i don't know that they are set up for emergency situations like yours.

Great to hear all the offers of support for baby stuff, for once the bubs arrive, but you need to get through your pregnancy first, financially survive, you are eating for three now.

What are the arrangements between you and your ex re the housekeys? ( this is rhetorical, you don't need to answer, just think about this stuff for your own benefit).
Does he still have housekeys to where you are living?
Is he planning to visit sometimes, has he spoken about ringing first?
I suspect there are issues here, that only a lawyer could walk you through - who gets to live in the home, who pays the mortgage, does the house have to be sold, possibility of locks being changed for your own peace of mind etc.

utility bills
you will need to pay utility bills to keep electricity/gas/water connected, during your pregnancy.
whose name are those bills in right now?
who is going to pay those bills?
what about right now? if he is just moved out, is he going to pay the utility bills, as they stand, as of today?

is his idea, of getting a boarder in (to rent a room in your house), realistic, in your opinion?

i know you're angry, hurting, feeling like he tricked you - those are all very valid
turn those emotions into getting yourself immediate help - $15 is nothing
I hope your cupboards/fridge were reasonably well stocked before he left

do you have a credit card/bank card - anything like that, in joint names?
if he's left you in the lurch like that, i would buy up big on an online supermarket site that delivers, before he takes your name off it. loo paper, washing powder, tinned food, cereal, long life milk - stuff that will keep.