Have you been paying anything on this loan yourself, or has she made all the payments?
Legally you are "jointly and severally liable" which means they can come after either of you for the full amount. Do not be taken in by her telling you it is your problem - it isn't, unless the lender decides to chase you. And, as others have said, as the loan is secured on her house it is much more likely they will chase her.
You say you are very short of money and will have extra costs - rent etc. Any debt of this nature should - so far as you are concerned - be treated as less important than your essential living costs. Perhaps the best solution at present would be that you just don't make any payments yourself and tell her that. If the lender contacts you you will need to give them an income and expenditure statement (showing your finances after you have moved out) and a payment offer - even if it is only a nominal �1 per month. You also tell them the debt is secured on her house and they should look to her and their security.
You may well end up with a bad credit record if the loan is defaulted so it would be better to secure your rented property (credit checks are often done by agents) before that happens.