Tia and shivaay i think both claim that their relation is based on trust but both knows that they are not loyal to each other
Tia is betraying shivaay and shivaay too is betraying her
Both have their own motives to marry each other
So i don't think tia's truth would affect shivaay much
But what my guess is tia's truth won't come out infront of shivaay and on the marriage it would be bride switch or anika wouldtry to stop the wedding where shivika would get married
Though anika would marry shivaay only to protect him and his family from evil and dangerous motives of tia but shivaay would presume that she married him because she had feelings for him and there he would lash out on anika because with his conversations he made very clear that they can never be together
And here comes the khoon khandaan jaap again causing massive explosion
Then would come Omkara and priyanka's past
Omkara and priyanka's past is definitely gonna shatter shivaay and it won't be because of broken trust
He would be angry on them but more then that he would be angry on himself because he would feel that he wasn't there when his brother and sister needed him the most
He couldn't prove to be the great wall as he claimed
He couldn't protect his siblings
And this thing would bring shivika closer than breaking them apart because shivaay would be so shattered and only person who would be able to handle him will be anika plus i am guessing that this truth will be out after ending tia's track