Do we have a chance at winning this case?

ok my fiance has 2 felony charges pending. we are going to court and i need to kno if we have a chance of winning. here is wat happened. we were at a friends house and my fiance was in the shower. the man whos house it was is a druggie and was high on heroin. he made a sexual comment toward me saying "since ur boyfriend is in the shower i guess that means i get to f*** u" and he got up to come towards me. i got up and left and so did another man that was w us. my boyfriend jumped out of the shower and beat the guys *** and left. the man called the police and said my fiance beat and robbed him. the man claimed he stole 45$ and his dope. my fiance never took anything. my fiance was on probation and ran from the police. He is being charged w strong armed robbery and aggrivated assult. do we have a chance of winning this case if myself and the other man that was there testifies on my fiance's behalf saying he only hit the man in my defense because he threatened to sexually assult me? there was no marks on the "victem". plus can we win the SAR charge if the police never recoverd wat was "stolen" and the "victem" is not creadible because he said my fiance stole his dope? i am pregnant w our first baby and i am trying my hardest to get my fiance off. i dont wanna raise my baby on my own. my fiance's criminal background is not good, he is a habitual offender and was on probation for a previous assult. Do we have a change?