Procedure in case Cheques issued as security and now not able to pay

I have given some cheques only as security to a individual, I had a broking business where he endured losses, since i was managing his account, i was pressured into repaying his trading losses, post that I paid almost 60% of the trading losses, since a few months my personal financial condition has gone from bad to worse, and I was not able to pay this guy anything, now he is deposited the cheque clearly knowing I am struggling financially, i have not taken any loan from this guy nor I am technically suppose to cover his losses as all the same happening in his own trading account. I am stuck really badly as I am not even in a position to hire a lawyer and this guy is pressurizing driving me to depression. what should I do? please help.