Help! My breasts ache and I am still in my first trimester. Will this continue until my baby is born or get better?

Breast pain. Breasts enlarge during the pregnancy and the stretching and fullness can be painful. The pain does eventually subside. Be patient and do not worry as this can cause your baby harm. Afterall you are living for two now! congrats!
It will get better. Breast tenderness is one of the most common symptoms of early pregnancy. It is so common that it is the tip-off to some women that they are, indeed, pregnant. It will get better after the first trimester. Wearing a supportive bra can help. Sports bras can be great because they are very supportive and will accommodate changes in breast size that may also happen at this time.