Dear Sweta,
Don’t feel bad about thoughts of past. Those are also part of existence. In old times many houses, a separate room were constructed, a store room, to keep all old articles, no more useable. So, just put all old thoughts or memories not relevant in your present in corner of mind, take a lesson from them, and let them go. Don’t link with your present life. If you will keep on chanting Sai name as such, then surely with effect of that one day, they themselves will leave you forever.
It is very tough to fight against ourselves, but that is where you gain real strength and wisdom. This is what you deserve too. So, Be strong, Keep on moving with confidence and faith in ultimate power of Baba.
May Sai Bless You!
om sri sai ram!