convicted in one crime can be used as witness in another case

the police on duty was drunken and misbehaving had exchange of words and he used abusive language there was exchange of words, and he threatened me and went away later, then after four days the CI of police station called on my personal number and threatened me and used abusive language and demanded me to come to police station otherwise i will face serious problems i just replied i cannot come without telling me proper reason, he kept on scolding me over the phone i have the full length call recording. later i came to know that I was booked with IPC 353 section still the case is running. police came to my home took me to police station and forcibly made me to sign on a paper in the police station that i am agreeing that i committed mistake and i am guilty, they showed in charge sheet witness of a person who was already convicted and arrested in a attemptive murder case on the same day when my incident has happened, does this witness is a valid witness i and locals personally know the witness not even in mere sight when the incident was happened and he was absconding because he attempted to kill some one and ran away. this is purely he want to make it because i scolded him being he is drunken,on duty using abusive language and. does the police in India allowed to scold and beat people as they wish or purposefully. what can be done with these baseless false case he filed against me. i have the call recording of CI and SI of police station talking rubbish to me and use of false witness in case. as of now i am just giving attendance. I just want to get justice the extent of problem they caused me 1. the CI and SI i have not shared my number still they got some how and they threatened me and scolded me badly though i did not misbehaved or not being cooperative i just asked the reason for calling and asking me to come to police station and threatening if i do not go they will spoil my life. 2. use of false witness, the witness himself was in murder case and on run he was not even at incident place he was on run to escape police. later witness talked to me and said that i am illiterate and in police station they forcibly made me to sign some papers. i intentionally not did and i am not witness in your case. and will cooperate with you to come out of this mess. how i can go ahead, i even want to teach a lesson to that police officers who misbehaved with me. my lawyer is very inexperienced he hardly come to a conclusion how to proceed. he just asks me to get compromise not to get into problems and police are dangrous, he has even no idea what he is doing even. can i change my lawyer if i want, because i smell he is sort of involved and he does not even talk in my favor.