You may want her to have a termination but she may want have the baby, or she may want a termination and you want her to keep the baby. This is obviously a very difficult decision but you must remember:
You have the right to explain your views, but not to force her to have the baby, or to terminate the pregnancy.
Think about how you really feel about the pregnancy, if you are feeling angry you must take time out before talking to her. Remember that you are both responsible for the pregnancy. If you are both unsure, take some time to think about what to do, this is a lifelong decision and should be discussed thoroughly. If you really want her to have a termination there is not much you can do except explain your views calmly and sensitively, but you must respect any decision that she makes, if she is going to keep the baby, you need to think about what your involvement will be and what kind of relationship you can have.
If you feel you need to talk to someone you can contact your GP about possible counselling and support.