I have been living with my partner who is now divorced for two years. He has two daughters one is 21 and the other is 23 years of age. I have my own dauhghter of 14 years of age living with us. Please can you help me. I have an obsessive jealously over his daughters which is threatening to finish us. I just can not control myself. As soon as I know he is seeing them or talking to them over the phone I have a kind of panic attack. They have never said a bad word about me and I like them as people but I can't handle the fact that my partner is their dad. Is this normal? Can you suggest anything I can do to help myself control this jealously.

Can you suggest anything I can do to help myself control this jealously.
Get to the bottom of it. I'm guessing it's due to a deep-seated insecurity, and a resulting need to have his undivided attention 100% of the time. It may take some counseling and therapy to uncover the underlying source of this insecurity, but you need to do it. Otherwise it will destroy this and every other close emotional relationship you try to develop. It's unfair and unhealthy to demand that much of another person.