Rhiannonsmoon - too true.

Have you talked to your boyfriend about how this isolation makes you feel? You have every right to want to be involved in his life. If people truly care about each other, they should want to share their lives. I mean, not necessarily everything, especially if you haven't been together for a particularly long time. But, shared social lives are pretty important. If he isn't including you in his social life, then it's normal to be hurt by that. That doesn't mean you have a low self-esteem. You seem like a very mature and accepting person, especially since you're okay with him still having his ex in his life.

If you haven't talked to him about it, I recommend doing so. Communication is key. If you have, then, I'm sorry but don't have much more advice than that.

I hope it works out for you. Best of luck.