From what you wrote, it appears that you have not let go of the "dream" you attached to this relationship....the dream of finding a perfect partner, of long-lasting love, of happiness, and so forth.
It would seem that you have not fully grieved the ending of the relationship and accepted that it is over. You write that you are in a new relationship and that this partner has many wonderful qualities...but...there is still the ghost of your past partner.
I encourage you to do the grieving you need to do to move beyond this past relationship. If you do not, you will stay stuck in the past and be unable to completely commit to this new partner or any partner.
Please let me know how you feel about the above response and then we can chat more.
Thankyou for your response - do you think its ok to be with someone else whilst you are still gireiving an old partner and you are right it was a dream.
It is very courageous of you to acknowledge your "truth" - that is, that you still had feelings for your former partner and had not completely let go of the relationship. Dreams are very powerful attachments! And, in your case, it held you in a kind of limbo.
As to being with someone whilst your are grieving...
To me, the issue is about the strength of that past attachment. When you are with your new partner are you "with" him or "with" your former partner? If you are primarily able to stay in the present then that's an indication that you've been moving on - and loosening that attachment. If, on the other hand, your mind is filled with the former partner, then there is considerable work you must do to loosen those bonds.
Many people form new partnerships to help them grieve a break-up. Often, these relationships do not last as this is not the healthiest for either person. From what you write, this is not what you did .... you had broken up some time ago and seemed to have formed an honest and caring relationship with your new partner.