Help...how do I get through my 12 year old daughters teenage years.

My daughter is 12 yrs old and very hard to live with. Understandably she has lots of difficulties and changes to contend with at the moment alongside hormonal changes.

I have separated from her dad and there is a new man in my life. This new man comes with a package which includes his two boys who are 7 and 3 yrs old. My daughter is finding things really difficult since the boys have been introduced to her and she is becoming quite angry and struggling to accept the changes.

I have tried talking to her on her own and reassuring her, telling her I love her etc…which seems to alleviate her anxieties at the time but issues seem to be going round in circles.

Can anyone advise on how to make my daughter feel more secure?